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/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 63e7179..52d19d7 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2410,7 +2410,7 @@
                                        const ParsedTemplateInfo &TemplateInfo,
                                        ParsingDeclRAIIObject *TemplateDiags) {
   if (Tok.is(tok::at)) {
-    if (getLangOpts().ObjC1 && NextToken().isObjCAtKeyword(tok::objc_defs))
+    if (getLangOpts().ObjC && NextToken().isObjCAtKeyword(tok::objc_defs))
       Diag(Tok, diag::err_at_defs_cxx);
     else
       Diag(Tok, diag::err_at_in_class);