cctools fails to build on 10.6.8 with new GCC: error: expected ';' before 'char'

[barracuda156]

Numerous errors of the following sort:

../arch.c:327:1: error: unknown type name '__private_extern__'
  327 | __private_extern__
      | ^~~~~~~~~~~~~~~~~~
../arch.c:329:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'get_stack_addr_from_flag'
  329 | get_stack_addr_from_flag(
      | ^~~~~~~~~~~~~~~~~~~~~~~~
../arch.c:340:1: error: unknown type name '__private_extern__'
  340 | __private_extern__
      | ^~~~~~~~~~~~~~~~~~
../arch.c:342:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'get_segalign_from_flag'
  342 | get_segalign_from_flag(
      | ^~~~~~~~~~~~~~~~~~~~~~
../arch.c:354:1: error: unknown type name '__private_extern__'
  354 | __private_extern__
      | ^~~~~~~~~~~~~~~~~~
../arch.c:356:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'get_shared_region_size_from_flag'
  356 | get_shared_region_size_from_flag(
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../arch.c:370:19: error: expected ';' before 'enum'
  370 | __private_extern__
      |                   ^
      |                   ;
  371 | enum bool
      | ~~~~               
make[2]: *** [arch.o] Error 1
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cctools/cctools/work/cctools-949.0.1/libstuff/profile_obj'
make[1]: *** [profile] Error 2
make[1]: *** Waiting for unfinished jobs....
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cctools/cctools/work/cctools-949.0.1/libstuff/dynamic_obj'
make[1]: *** [dynamic] Error 2
make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_cctools/cctools/work/cctools-949.0.1/libstuff'
make: *** [all] Error 1

[kencu (Ken)]

this fixes those, but then there is another issue with some clang-specific availability functions.