[Driver][FreeBSD] Correct driver behavior if a triple is provided without a version

While looking at other usage of getOSMajorVersion() I noticed if a version number is not
included in the FreeBSD triple it won't include the --hash-style=both linker option or
not disable the use of .init_array. Without a version should be the latest.

FreeBSD 8 and 9 are no longer supported. So simplify things with the version handling
as well.

Reviewed By: dim

Differential Revision: https://reviews.llvm.org/D144341