[Driver] Default to contemporary FreeBSD profiling behaviour

Prior to FreeBSD 14, FreeBSD provided special _p.a libraries for use
with -pg.  They are no longer used or provided.  If the target does
not specify a major version (e.g. amd64-unknown-freebsd, rather than
amd64-unknown-freebsd12) default to the new behaviour.

Differential Revision:	https://reviews.llvm.org/D114396