[libc++][C++03] Fix libc++ includes (#109000)

This is part of the "Freezing C++03 headers" proposal explained in
https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319/58.

This patch updates the include paths used in `__cxx03/` to refer to the
`__cxx03/` headers.

GitOrigin-RevId: 73fbae8383c0994bcc2a5d5307883f53a1fe7d9c
1010 files changed