VSCode's Pylance extension informed me, and text searching confirmed,
that these imports are unused. I believe we should be able to remove
them harmlessly.
Post review feedback on D157364. Don't section the __std_clang_module header by macro, put the headers in alphabetical order and repeat the macro guards. Restore header_information.header_restrictions.
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D158133
Use header_information to generate the __std_clang_module header. Instead of using lit_header_restrictions like the manually written header did, make a new header_include_requirements to codify what can be included rather than what can be fully tested.
Reviewed By: Mordante, #libc
Differential Revision: https://reviews.llvm.org/D157364
