Centralize header changes to respective repos and remove headers from this repo

Headers right now are in a really weird place. We have libc and libcxx headers both in the musl and llvm-project repos as well as copies in this repo that samples and such build against. This leads to a problem where fixes can get pushed to one side and not to the other, and just causes general confusion.

With a better build system in the pipeline, these headers should be removed from the repo, and should be copied into include/ as part of the build process. This way, any changes or fixes are centralized to their respective repositories where they can be isolated and tested.

Ultimately the only headers that should be left in this repository are orbis/PS4-specific headers.

As such, multiple headers will need to have fixes/changes made in this repository backported to the musl and llvm-project repositories.

The following C headers need to be ported:

[x] include/bits/alltypes.h
[x] include/bits/dirent.h
[x] include/bits/fcntl.h
[x] include/bits/ioctl.h
[x] include/bits/limits.h
[x] include/bits/stat.h
[x] include/bits/statfs.h
[x] include/netinet/in.h
[x] include/sys/ioctl.h
[x] include/sys/socket.h
[x] include/endian.h
[x] include/math.h
[x] include/pthread.h

The following C++ headers need to be ported:

[x] include/c++/v1/__config
[x] include/c++/v1/__threading_support
[x] include/c++/v1/cmath
[x] include/c++/v1/compare
[x] include/c++/v1/module.modulemap
[x] include/c++/v1/ostream
[x] include/c++/v1/variant
[x] include/c++/v1/vector
[x] include/c++/v1/version

OpenOrbis / OpenOrbis-PS4-Toolchain

Centralize header changes to respective repos and remove headers from this repo #166