[clang-tidy] Merge common code between llvmlibc-restrict-system-libc-headers and...

[clang-tidy] Merge common code between llvmlibc-restrict-system-libc-headers and portability-restrict-system-includes

Summary:
Made llvmlibc::RestrictSystemLibcHeadersCheck a subclass of protability::RestrictSystemIncludesCheck to re-use common code between the two.
This also adds the ability to white list linux development headers.

Reviewers: aaron.ballman

Reviewed By: aaron.ballman

Subscribers: mgorny, xazax.hun, MaskRay, cfe-commits, sivachandra

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D76395