irc/gseen.mod: set LLD_UNSAFE to link using ld.bfd

lld has no built-in search paths (/lib, /usr/lib). Normally the linker
is invoked from the compiler driver, and the search paths are added by
the compiler. If lld is invoked directly library search paths must be
specified explicitly, with -L/lib -L/usr/lib.

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