lang/fpc: Set LLD_UNSAFE

fpc produces and needs to link an object file with invalid section
header alignment, which lld refuses to do. The build fails with:

/usr/bin/ld: error: x86_64/units/x86_64-freebsd/i_linux.o: \

invalid alignment of section headers

Setting LLD_UNSAFE makes the port link with ld.bfd instead.

PR: 222172
Approved by: portmgr (LLD_UNSAFE blanket)
Sponsored by: The FreeBSD Foundation