Don't hardcode GCC_VERSION for Xcode in standalone.gypi.

This fixes standalone command-line Xcode compilation with Xcode 5.x.

R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/138443008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18785 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

build/standalone.gypi

@@ -299,7 +299,6 @@
           'GCC_INLINES_ARE_PRIVATE_EXTERN': 'YES',
           'GCC_SYMBOLS_PRIVATE_EXTERN': 'YES',      # -fvisibility=hidden
           'GCC_THREADSAFE_STATICS': 'NO',           # -fno-threadsafe-statics
-          'GCC_VERSION': 'com.apple.compilers.llvmgcc42',
           'GCC_WARN_ABOUT_MISSING_NEWLINE': 'YES',  # -Wnewline-eof
           'GCC_WARN_NON_VIRTUAL_DESTRUCTOR': 'YES', # -Wnon-virtual-dtor
           # MACOSX_DEPLOYMENT_TARGET maps to -mmacosx-version-min