[libc++] Fix libcxx build on 32bit architectures with 64bit time_t defaults e.g. riscv32

Patch by Khem Raj.

Differential Revision: https://reviews.llvm.org/D85095

GitOrigin-RevId: 85b9c5ccc172a1e61c7ecaaec4752587cb6f1e26
1 file changed