Use st_mtim if st_mtime is macro, fix #1510

In POSIX.1-2008, sys_stat has a st_mtim member and a st_mtime backward
compatibility macro. Should help avoid hardcoding platform detection.

Bug: 190084016
Test: m out/soong/host/linux-x86/bin/ninja with musl
(cherry picked from commit 567815df38a2ff54ad7478a90bd75c91e434236a)
Change-Id: If073a90b26d7dd4f3149ed76acc0da817bf07775
1 file changed