util/u_printf: do not double print format string with unused arugments
the CL CTS added a new test being printf("\n", "foo"), but we ended up printing the new line twice. If we can't find a specifier anymore, ignore the argument as after the loop processing all arguments we'll print the remaining format string anyway. Cc: mesa-stable Reviewed-by:Jesse Natalie <jenatali@microsoft.com> Part-of: <mesa/mesa!30574> (cherry picked from commit 40802698)