[libc++] Add a new FILE_DEPENDENCIES parser

Instead of considering all the .dat files to be dependencies of a test,
only consider those that are listed in FILE_DEPENDENCIES.

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 7efbd851adf3124f7e756c37348ddd3ff7427ad7
19 files changed