Move _p.a profiling archives under MK_INSTALLLIB

_p.a are just a special case of .a archives, and should not be installed
if WITHOUT_INSTALLLIB is set.

MFC after: 1 week
Sponsored by: The FreeBSD Foundation

(cherry picked from commit fc073e6743a989c9d0b8f619ce0f903271c0db2e)
(cherry picked from commit 0421d8bdef00c710a38cb11547a91c8fde2c5c8c)