Fix testcases for PR c/78304
The testcases as written made assumptions about size_t and long
being invalid for use with "%u".
We only need some invalid type, so this patch converts them to
attempt a "const char *" with "%u", which should be invalid for
every target.
gcc/testsuite/ChangeLog:
PR c/78304
* gcc.dg/format/pr78304.c: Convert argument from integral type
to a pointer.
* gcc.dg/format/pr78304-2.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@244502 138bc75d-0d04-0410-961f-82ee72b054a4