tools/rtla: Use pkg-config in lib_setup of Makefile.config

This allows to build against libtraceevent and libtracefs installed
in non-standard locations.

Signed-off-by: Guilherme Amadio <amadio@gentoo.org>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
Tested-by: Leo Yan <leo.yan@arm.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20240712194511.3973899-5-amadio@gentoo.org


Signed-off-by: Namhyung Kim <namhyung@kernel.org>