Move OFED libraries libmlx5.so.1 and libibverbs.so.1 to /lib.

The is required because libpcap.so depends on the libraries when OFED
is enabled.

Reviewed by: bdrewery, hselasky
Sponsored by: Mellanox Technologies
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D16230