ClangImporter: adjust for SVN r345637

`ObjC1` has been removed from clang.  Use `ObjC` to detect if Objective-C
language support is enabled.

Author: compnerd

lib/ClangImporter/ImportType.cpp

@@ -1453,7 +1453,7 @@ ImportedType ClangImporter::Implementation::importType(
   // This bans some trickery that the redefinition types enable, but is a more
   // sane model overall.
   auto &clangContext = getClangASTContext();
-  if (clangContext.getLangOpts().ObjC1) {
+  if (clangContext.getLangOpts().ObjC) {
     if (clangContext.hasSameUnqualifiedType(
           type, clangContext.getObjCIdRedefinitionType()) &&
         !clangContext.hasSameUnqualifiedType(