rtla: Check pkg-config install

The tool pkg-config used to check libtraceevent and libtracefs, if not
installed, it will report the libs not found, even though they have
already been installed.

Before:
libtraceevent is missing. Please install libtraceevent-dev/libtraceevent-devel
libtracefs is missing. Please install libtracefs-dev/libtracefs-devel

After:
Makefile.config:10: *** Error: pkg-config needed by libtraceevent/libtracefs is missing
on this system, please install it.

Link: https://lore.kernel.org/20250808040527.2036023-2-chen.dylane@linux.dev


Fixes: 01474dc7 ("tools/rtla: Use tools/build makefiles to build rtla")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>