[CompilerRT] Fix build of compiler-rt with musl

Use the correct types for OFF_T, __sanitizer_time_t and
__sanitizer_dirent and forward time_t related functions
 to fix using compiler-rt with 32-bit musl libc.

Also redirect the time_t functions that are affected by
https://musl.libc.org/time64.html to use their 64-bit
ABI names.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D119358