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/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index bba1ef1..a8d80a0 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1024,7 +1024,7 @@
     return InputKind::OpenCL;
   if (LangOpts.CUDA)
     return InputKind::CUDA;
-  if (LangOpts.ObjC1)
+  if (LangOpts.ObjC)
     return LangOpts.CPlusPlus ? InputKind::ObjCXX : InputKind::ObjC;
   return LangOpts.CPlusPlus ? InputKind::CXX : InputKind::C;
 }