[PATCH] Partial revert of 183015

[Richard Smith]

================
Comment at: include/clang/Basic/Builtins.def:740
@@ -739,3 +739,3 @@
 
 // Non-C library functions, active in GNU mode only.
 LIBBUILTIN(alloca, "v*z",         "f",     "stdlib.h", ALL_GNU_LANGUAGES)
----------------
Please update this comment to explain why we don't have ALL_GNU_LANGUAGES for those builtins with the 'j' flag.


http://reviews.llvm.org/D3369