[libc] Fix missing UINTMAX_WIDTH (#87092)

In patch #82461 the sprintf tests were made to use UINTMAX_WIDTH which
isn't defined on all systems. This patch changes it to
sizeof(uintmax_t)*CHAR_BIT which is more portable.

GitOrigin-RevId: 838b118d394138a746ffb4c113fb97b0f8904bd2
1 file changed