llvm-6.0: python27 dependency

[nerdling (Jeremy Lavergne)]

Was compiling dependencies for lilypond-devel today (with trace mode) and had the build fail at llvm-6.0.

I checked the log, where I saw configure stopped after not finding python27. Adding python27 to the depends_lib resolved the issue.

--- a/lang/llvm-6.0/Portfile
+++ b/lang/llvm-6.0/Portfile
@@ -32,7 +32,7 @@ if {${subport} eq "llvm-${llvm_version}"} {
                         around a well specified code representation known as \
                         the LLVM intermediate representation ("LLVM IR").
 
-    depends_lib         port:libedit port:libffi port:ncurses path:lib/libxar.dylib:xar port:zlib
+    depends_lib         port:libedit port:libffi port:ncurses path:lib/libxar.dylib:xar port:zlib port:python27
     depends_run         bin:perl:perl5 port:llvm_select
 } elseif {${subport} eq "clang-${llvm_version}"} {
     homepage            https://clang.llvm.org/