sysutils/unieject: set LLD_UNSAFE

unieject fails to link with lld as the system linker due to shared
library protected visibility symbol preemption issues. Set LLD_UNSAFE
to use ld.bfd.

Errors are of the form:

/usr/bin/ld: error: cannot preempt symbol: libunieject_getdevice

defined in ./.libs/libunieject.so
referenced by unieject.c

unieject-unieject.o:(main)

PR: 214864
Approved by: portmgr (LLD_UNSAFE blanket)
Sponsored by: The FreeBSD Foundation