c-c++-common/builtin-has-attribute-4.c: Require visibility.

Another missed attribute-visibility-requirement, causing a failure for
e.g. mmix-knuth-mmixware.  Committed as obvious.

gcc/testsuite:
	* c-c++-common/builtin-has-attribute-4.c: Require visibility.

gcc/testsuite/c-c++-common/builtin-has-attribute-4.c

@@ -4,6 +4,7 @@
    { dg-options "-Wall -ftrack-macro-expansion=0" }
    { dg-options "-Wall -Wno-narrowing -Wno-unused -ftrack-macro-expansion=0" { target c++ } }
    { dg-additional-options "-DSKIP_ALIAS" { target *-*-darwin* } }
+   { dg-require-visibility "hidden" }
 */
 
 #define ATTR(...) __attribute__ ((__VA_ARGS__))