[libc] Fix too long number in strtoul_test

I think this is the last windows type conversion fix, the rest of the
build seems to be okay.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D108659

GitOrigin-RevId: fdee2d768d5f1a242952f5da2a7e2b13a9ecabd5
1 file changed