linux-headers

• Provide before musl-headers in stage 1 (toolchain) to prevent overwriting libc headers
• INSTALL_HDR_PATH="$CRSD"/usr only works with headers_install target (not headers)
• headers_install requires rsync
• find usr/include -name '.*' -delete does not remove Makefile and headers_check.pl
• Remove usr/include/drm to use headers from libdrm
• The headers_check target runs a few trivial sanity checks on the headers before install
  • checks if a header includes something nonexistent
  • checks if the declarations inside the headers are sane
  • checks if kernel internals are leaked into user space
  • not that useful for release tarballs but could come in handy when working with kernel git trees
• mrproper requires ARCH