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/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index d158745..92a421d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1915,7 +1915,7 @@
   if (IK.getLanguage() == InputKind::Asm) {
     Opts.AsmPreprocessor = 1;
   } else if (IK.isObjectiveC()) {
-    Opts.ObjC1 = Opts.ObjC2 = 1;
+    Opts.ObjC = 1;
   }
 
   if (LangStd == LangStandard::lang_unspecified) {
@@ -2246,7 +2246,7 @@
 
   Opts.GPURelocatableDeviceCode = Args.hasArg(OPT_fgpu_rdc);
 
-  if (Opts.ObjC1) {
+  if (Opts.ObjC) {
     if (Arg *arg = Args.getLastArg(OPT_fobjc_runtime_EQ)) {
       StringRef value = arg->getValue();
       if (Opts.ObjCRuntime.tryParse(value))