[ObjC] Improve error message for a malformed objc-type-name

If the type didn't exist, we used to emit a really bad error:

t.m:3:12: error: expected ')'
-(nullable NoSuchType)foo3;
           ^

rdar://50925632

llvm-svn: 364489
diff --git a/clang/lib/Parse/ParseObjc.cpp b/clang/lib/Parse/ParseObjc.cpp
index c2e73d5..a8d6f7f 100644
--- a/clang/lib/Parse/ParseObjc.cpp
+++ b/clang/lib/Parse/ParseObjc.cpp
@@ -1247,11 +1247,11 @@
   BalancedDelimiterTracker T(*this, tok::l_paren);
   T.consumeOpen();
 
-  SourceLocation TypeStartLoc = Tok.getLocation();
   ObjCDeclContextSwitch ObjCDC(*this);
 
   // Parse type qualifiers, in, inout, etc.
   ParseObjCTypeQualifierList(DS, context);
+  SourceLocation TypeStartLoc = Tok.getLocation();
 
   ParsedType Ty;
   if (isTypeSpecifierQualifier() || isObjCInstancetype()) {