Revert "musl: renamed pkg dir (linux-header -> linux) fixing linux-header patching"

This reverts commit d0201f400f5d871be5edf0318961c8900180d23f.
musl: fixed parse-config-9 to not map the linux-header package to the linux package

Applying libc-compat.h related patches to the kernel itself breaks the build.
It doesn't really make much sense to do that anyway because it is highly
unlikely that there will be any musl dpecific patch for the kernel itself.