root6: Undefined symbol "_environ" on Mac OS X 10.7

[mojca (Mojca Miklavec)]

The update in r135166 broke the build on Lion:

• ​https://sft.its.cern.ch/jira/browse/ROOT-7271
• ​https://build.macports.org/builders/buildports-lion-x86_64/builds/28378

[ 44%] Building CXX object core/meta/CMakeFiles/Cling.dir/__/metautils/src/TMetaUtils.cxx.o
cd /path/to/root6/work/build/core/meta && /opt/local/bin/clang++-mp-3.4   -DCling_EXPORTS -pipe -Os -arch x86_64 -stdlib=libc++  -m64 -pipe -W -Wall -Woverloaded-virtual -fsigned-char -fno-common -Qunused-arguments -pthread -std=c++11 -Wno-deprecated-declarations -Wc++11-narrowing -Wsign-compare -Wsometimes-uninitialized -Wconditional-uninitialized -Wheader-guard -Warray-bounds -Wcomment -Wtautological-compare -Wstrncat-size -Wloop-analysis -Wbool-conversion -stdlib=libc++ -DR__HAVE_CONFIG -Wno-conditional-uninitialized -O2 -DNDEBUG -arch x86_64 -fPIC -I/path/to/root6/work/build/include/root -I/path/to/root6/work/build/include -I/path/to/root6/work/root-9ab0642adeca5d3703783bdbfeebfca86ea22af9/interpreter/llvm/src/include -I/path/to/root6/work/build/interpreter/llvm/src/include -I/path/to/root6/work/root-9ab0642adeca5d3703783bdbfeebfca86ea22af9/interpreter/llvm/src/tools/clang/include -I/path/to/root6/work/build/interpreter/llvm/src/tools/clang/include -I/path/to/root6/work/root-9ab0642adeca5d3703783bdbfeebfca86ea22af9/interpreter/cling/include -I/path/to/root6/work/root-9ab0642adeca5d3703783bdbfeebfca86ea22af9/io/io/inc    -fvisibility-inlines-hidden -fno-strict-aliasing -Wno-unused-parameter -Wwrite-strings -Wno-long-long -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -o CMakeFiles/Cling.dir/__/metautils/src/TMetaUtils.cxx.o -c /path/to/root6/work/root-9ab0642adeca5d3703783bdbfeebfca86ea22af9/core/metautils/src/TMetaUtils.cxx
Linking CXX shared library ../../lib/libCling.so
cd /path/to/root6/work/build/core/meta && /opt/local/bin/cmake -E cmake_link_script CMakeFiles/Cling.dir/link.txt --verbose=ON
/opt/local/bin/clang++-mp-3.4  -pipe -Os -arch x86_64 -stdlib=libc++  -m64 -pipe -W -Wall -Woverloaded-virtual -fsigned-char -fno-common -Qunused-arguments -pthread -std=c++11 -Wno-deprecated-declarations -Wc++11-narrowing -Wsign-compare -Wsometimes-uninitialized -Wconditional-uninitialized -Wheader-guard -Warray-bounds -Wcomment -Wtautological-compare -Wstrncat-size -Wloop-analysis -Wbool-conversion -stdlib=libc++ -DR__HAVE_CONFIG -Wno-conditional-uninitialized -O2 -DNDEBUG -arch x86_64 -dynamiclib -Wl,-headerpad_max_install_names -m64 -single_module -Wl,-dead_strip_dylibs  -L/opt/local/lib -Wl,-headerpad_max_install_names -arch x86_64 -compatibility_version 6.0.0 -current_version 6.3.3 -o ../../lib/libCling.6.03.03.so -install_name /opt/local/libexec/root6/lib/root/libCling.6.so CMakeFiles/Cling.dir/__/metautils/src/TMetaUtils.cxx.o CMakeFiles/MetaLLVM.dir/src/TCling.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingBaseClassInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingCallbacks.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingCallFunc.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingClassInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingDataMemberInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingMethodArgInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingMethodInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingTypedefInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingTypeInfo.cxx.o CMakeFiles/MetaLLVM.dir/src/TClingValue.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/BaseSelectionRule.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/ClassSelectionRule.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/VariableSelectionRule.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/RStl.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/Scanner.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/SelectionRules.cxx.o ../metautils/CMakeFiles/MetaUtilsLLVM.dir/src/XMLReader.cxx.o ../../interpreter/llvm/src/lib/libclingInterpreter.a ../../interpreter/llvm/src/lib/libclingMetaProcessor.a ../../interpreter/llvm/src/lib/libclingUtils.a /opt/local/lib/libncurses.dylib ../../lib/libRIO.6.03.03.so ../../interpreter/llvm/src/lib/libLLVMMCJIT.a ../../interpreter/llvm/src/lib/libLLVMOrcJIT.a ../../interpreter/llvm/src/lib/libLLVMExecutionEngine.a ../../interpreter/llvm/src/lib/libLLVMRuntimeDyld.a ../../interpreter/llvm/src/lib/libLLVMX86AsmParser.a ../../interpreter/llvm/src/lib/libLLVMX86CodeGen.a ../../interpreter/llvm/src/lib/libLLVMAsmPrinter.a ../../interpreter/llvm/src/lib/libLLVMSelectionDAG.a ../../interpreter/llvm/src/lib/libLLVMCodeGen.a ../../interpreter/llvm/src/lib/libLLVMTarget.a ../../interpreter/llvm/src/lib/libLLVMX86Desc.a ../../interpreter/llvm/src/lib/libLLVMX86AsmPrinter.a ../../interpreter/llvm/src/lib/libLLVMX86Utils.a ../../interpreter/llvm/src/lib/libLLVMX86Disassembler.a ../../interpreter/llvm/src/lib/libLLVMX86Info.a ../../interpreter/llvm/src/lib/libLLVMMCDisassembler.a ../../interpreter/llvm/src/lib/libclangCodeGen.a ../../interpreter/llvm/src/lib/libLLVMBitWriter.a ../../interpreter/llvm/src/lib/libLLVMipo.a ../../interpreter/llvm/src/lib/libLLVMVectorize.a ../../interpreter/llvm/src/lib/libLLVMInstrumentation.a ../../interpreter/llvm/src/lib/libLLVMObjCARCOpts.a ../../interpreter/llvm/src/lib/libLLVMScalarOpts.a ../../interpreter/llvm/src/lib/libLLVMInstCombine.a ../../interpreter/llvm/src/lib/libclangFrontend.a ../../interpreter/llvm/src/lib/libclangDriver.a ../../interpreter/llvm/src/lib/libLLVMOption.a ../../interpreter/llvm/src/lib/libclangParse.a ../../interpreter/llvm/src/lib/libclangSerialization.a ../../interpreter/llvm/src/lib/libclangSema.a ../../interpreter/llvm/src/lib/libclangEdit.a ../../interpreter/llvm/src/lib/libclangAnalysis.a ../../interpreter/llvm/src/lib/libclangAST.a ../../interpreter/llvm/src/lib/libclangLex.a ../../interpreter/llvm/src/lib/libclangBasic.a ../../interpreter/llvm/src/lib/libLLVMIRReader.a ../../interpreter/llvm/src/lib/libLLVMAsmParser.a ../../interpreter/llvm/src/lib/libLLVMLinker.a ../../interpreter/llvm/src/lib/libLLVMTransformUtils.a ../../interpreter/llvm/src/lib/libLLVMipa.a ../../interpreter/llvm/src/lib/libLLVMAnalysis.a ../../interpreter/llvm/src/lib/libLLVMProfileData.a ../../interpreter/llvm/src/lib/libLLVMObject.a ../../interpreter/llvm/src/lib/libLLVMMCParser.a ../../interpreter/llvm/src/lib/libLLVMMC.a ../../interpreter/llvm/src/lib/libLLVMBitReader.a ../../interpreter/llvm/src/lib/libLLVMCore.a ../../interpreter/llvm/src/lib/libLLVMSupport.a -lcurses -lpthread -lz -lm ../../lib/libThread.6.03.03.so ../../lib/libCore.6.03.03.so -Wl,-rpath,/opt/local/lib 
Undefined symbols for architecture x86_64:
  "_environ", referenced from:
      __ZL7ExecuteRN4llvm3sys11ProcessInfoENS_9StringRefEPPKcS6_PPKS3_jPNSt3__112basic_stringIcNSA_11char_traitsIcEENSA_9allocatorIcEEEE in libLLVMSupport.a(Program.cpp.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [lib/libCling.6.03.03.so] Error 1
make[2]: Leaving directory `/path/to/root6/work/build'
make[1]: *** [core/meta/CMakeFiles/Cling.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
Linking CXX executable ../../bin/rootcling