With this invoking one of the utilities with `-h` will display the manpage.

Since quark is not a "system utility", we can't expect people to go to the
trouble of installing manpages, and typing `man ./quark-mon.8` is a pain. It's
also likely that the binary is sent somewhere and thus the man relationship was
lost.

I had to write a mini-utility to embed the manpage, it's a bit sad that there
isn't a `mandoc -T c` to export the manpage as a C struct.

Arm64 cross compilation gets a little bit trickier:

In order to build quark-mon, quark-btf and quark-test, it needs to build
manpage.h, and to build manpage.h it needs to build man-embedder. But it can't
build man-embedder for arm64, since we must be able to execute it!

We fix it by cheating the order build, we force manpages.h to be evaluated
before `all` in the host system. Which pulls man-embedder for the host and
generates manpage.h. The only drawback is that man-embedder will stay built for
the host system, which is fine since it's a build-system executable.