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/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index fc3fa5d..792171a 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -4165,7 +4165,7 @@
   CheckAbsoluteValueFunction(TheCall, FDecl);
   CheckMaxUnsignedZero(TheCall, FDecl);
 
-  if (getLangOpts().ObjC1)
+  if (getLangOpts().ObjC)
     DiagnoseCStringFormatDirectiveInCFAPI(*this, FDecl, Args, NumArgs);
 
   unsigned CMId = FDecl->getMemoryFunctionKind();