linuxHeaders: 4.19.16 -> 5.5

Linux has reworked its header install process in
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=59b2bd05f5f4dc62979c2e82ddd384f07e8f10bc
It has introduced `make headers` that prepares the headers in ./usr/include, and
made `make headers_install` copy the headers from there using rsync.