NFC: Remove the ObjC1/ObjC2 distinction from clang (and related projects)

We haven't supported compiling ObjC1 for a long time (and never will again), so
there isn't any reason to keep these separate. This patch replaces
LangOpts::ObjC1 and LangOpts::ObjC2 with LangOpts::ObjC.

Differential revision: https://reviews.llvm.org/D53547

llvm-svn: 345637
diff --git a/clang/lib/Basic/Builtins.cpp b/clang/lib/Basic/Builtins.cpp
index a3210ba..7e7f67c 100644
--- a/clang/lib/Basic/Builtins.cpp
+++ b/clang/lib/Basic/Builtins.cpp
@@ -68,7 +68,7 @@
   bool GnuModeUnsupported = !LangOpts.GNUMode && (BuiltinInfo.Langs & GNU_LANG);
   bool MSModeUnsupported =
       !LangOpts.MicrosoftExt && (BuiltinInfo.Langs & MS_LANG);
-  bool ObjCUnsupported = !LangOpts.ObjC1 && BuiltinInfo.Langs == OBJC_LANG;
+  bool ObjCUnsupported = !LangOpts.ObjC && BuiltinInfo.Langs == OBJC_LANG;
   bool OclC1Unsupported = (LangOpts.OpenCLVersion / 100) != 1 &&
                           (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES ) ==  OCLC1X_LANG;
   bool OclC2Unsupported = LangOpts.OpenCLVersion != 200 &&