[compiler-rt][builtins] Use explicitly-sized integer types for LibCalls

Use s[iu]_int instead of `(unsigned) int` and d[ui]_int instead of
`(unsigned) long long` for LibCall arguments.

Note: the `*vfp` LibCall versions were NOT touched.

Reviewed By: aykevl

Differential Revision: https://reviews.llvm.org/D86546