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/InitHeaderSearch.cpp b/clang/lib/Frontend/InitHeaderSearch.cpp
index 8a70404..deedb22 100644
--- a/clang/lib/Frontend/InitHeaderSearch.cpp
+++ b/clang/lib/Frontend/InitHeaderSearch.cpp
@@ -616,11 +616,11 @@
 
   for (auto &Include : IncludePath)
     if (Include.first == System || Include.first == ExternCSystem ||
-        (!Lang.ObjC1 && !Lang.CPlusPlus && Include.first == CSystem) ||
-        (/*FIXME !Lang.ObjC1 && */ Lang.CPlusPlus &&
+        (!Lang.ObjC && !Lang.CPlusPlus && Include.first == CSystem) ||
+        (/*FIXME !Lang.ObjC && */ Lang.CPlusPlus &&
          Include.first == CXXSystem) ||
-        (Lang.ObjC1 && !Lang.CPlusPlus && Include.first == ObjCSystem) ||
-        (Lang.ObjC1 && Lang.CPlusPlus && Include.first == ObjCXXSystem))
+        (Lang.ObjC && !Lang.CPlusPlus && Include.first == ObjCSystem) ||
+        (Lang.ObjC && Lang.CPlusPlus && Include.first == ObjCXXSystem))
       SearchList.push_back(Include.second);
 
   for (auto &Include : IncludePath)