JavaScriptCore uses PLATFORM(MAC) when it means OS(DARWIN)

https://bugs.webkit.org/show_bug.cgi?id=99683

Reviewed by Anders Carlsson.

* jit/ThunkGenerators.cpp:
* tools/CodeProfile.cpp:
(JSC::symbolName):
(JSC::CodeProfile::sample):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162266 268f45cc-cd09-0410-ab3c-d52691b4dbfc