rtla/Makefile: Properly handle dependencies

Linus had a problem compiling RTLA, saying:

"[...] I wish the tracing tools would do a bit more package
checking and helpful error messages too, rather than just
fail with:

    fatal error: tracefs.h: No such file or directory"

Which is indeed not a helpful message. Update the Makefile, adding
proper checks for the dependencies, with useful information about
how to resolve possible problems.

For example, the previous error is now reported as:

    $ make
    ********************************************
    ** NOTICE: libtracefs version 1.3 or higher not found
    **
    ** Consider installing the latest libtracefs from your
    ** distribution, e.g., 'dnf install libtracefs' on Fedora,
    ** or from source:
    **
    **  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
    **
    ********************************************

These messages are inspired by the ones used on trace-cmd, as suggested
by Stevel Rostedt.

Link: https://lore.kernel.org...