Wbuiltin-declaration-mismatch-4.c: accept long long in warning for llp64

Wbuiltin-declaration-mismatch-4.c: accept long long in warning for llp64

llp64 targets like mingw-w64 will print:
gcc/testsuite/gcc.dg/Wbuiltin-declaration-mismatch-4.c:80:17: warning: ‘memset’ argument 3 promotes to ‘ptrdiff_t’ {aka ‘long long int’} where ‘long long unsigned int’ is expected in a call to built-in function declared without prototype [-
Wbuiltin-declaration-mismatch]
Change the regex pattern to accept it.

Signed-off-by: Jonathan Yong <10walls@gmail.com>
gcc/testsuite/ChangeLog:

	* gcc.dg/Wbuiltin-declaration-mismatch-4.c: Make diagnostic
	accept long long.