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/Sema.cpp b/clang/lib/Sema/Sema.cpp
index d5d9228..d6fe37f 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -152,7 +152,7 @@
   for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
     NSNumberLiteralMethods[I] = nullptr;
 
-  if (getLangOpts().ObjC1)
+  if (getLangOpts().ObjC)
     NSAPIObj.reset(new NSAPI(Context));
 
   if (getLangOpts().CPlusPlus)
@@ -214,7 +214,7 @@
 
 
   // Initialize predefined Objective-C types:
-  if (getLangOpts().ObjC1) {
+  if (getLangOpts().ObjC) {
     // If 'SEL' does not yet refer to any declarations, make it refer to the
     // predefined 'SEL'.
     DeclarationName SEL = &Context.Idents.get("SEL");