libpfm4 and babeltrace are enabled if they're found, so add
PACKAGECONFIGs so that our configuration is explicit.
(From OE-Core rev: 8818a259495310f3054abc2918771587e6f82ae9)
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>