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/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 8b87a20..05e47af 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -2648,9 +2648,9 @@
   else if (LangOpts.RenderScript)
     Lang = InputKind::RenderScript;
   else if (LangOpts.CPlusPlus)
-    Lang = LangOpts.ObjC1 ? InputKind::ObjCXX : InputKind::CXX;
+    Lang = LangOpts.ObjC ? InputKind::ObjCXX : InputKind::CXX;
   else
-    Lang = LangOpts.ObjC1 ? InputKind::ObjC : InputKind::C;
+    Lang = LangOpts.ObjC ? InputKind::ObjC : InputKind::C;
 
   InputKind::Format Fmt = InputKind::Source;
   if (LangOpts.getCompilingModule() == LangOptions::CMK_ModuleMap)