Don't accept qualified 'int' main return types in C++ or standard C mode

C++ [basic.start.main]p1: "It shall have a return type of type int"

ISO C is also clear about this, so only accept 'int' with qualifiers in GNUMode
C.

llvm-svn: 212171
diff --git a/clang/test/Sema/c89.c b/clang/test/Sema/c89.c
index b746d38..c9e81f1 100644
--- a/clang/test/Sema/c89.c
+++ b/clang/test/Sema/c89.c
@@ -111,6 +111,8 @@
 
 void main() {} /* expected-error {{'main' must return 'int'}} */
 
+const int main() {} /* expected-error {{'main' must return 'int'}} */
+
 long long ll1 = /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */
          -42LL; /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */
 unsigned long long ull1 = /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */