devel/libcfg: set LLD_UNSAFE

This port passes ${LDFLAGS} to both the compiler driver and directly
to the linker, which is not valid. Revert to using ld.bfd for now which
produces output with a bogus entry, but does not fail to link.

Bump portrevision.

PR: 221778
Submitted by: emaste@
Approved by: rodrigo@ (maintainer)