Instead of unconditionally including sys/param.h in
macro-fundamental.h which itself includes a bunch of other unnecessary
headers, let's override it with an empty file to avoid it from overriding
our MAX() macro. We can't make including it an error as it's included (
for seemingly no good reason) by <resolv.h>.
These glibc headers conflicts with the corresponding linux headers
(<linux/in.h> and <linux/if.h>) and impose an include order (the glibc one
has to be included before any linux header is included). This makes sorting
includes a royal pain so let's define our own versions of these headers using
various linux headers to do all the work and filling in the missing bits
ourselves.
The header requires struct sockaddr declared. So, otherwise, we need to
include sys/socket.h earlier than linux/vm_sockets.h.
Let's make the header includable at any place.
Even though these are in our tree, we should still treat them as
system includes which helps various tools (clangd, iwyu, ...) understand
that these are system includes and <> should be used instead of "".
