Makerules: Generate shlib.lds with -fuse-ld=bfd

Makerules: Generate shlib.lds with -fuse-ld=bfd

lld does not dump a linker script with --verbose (it does not use a
linker script driven design and lots of linker processing is not
serializable as a linker script anyway).  With the default
--with-default-link=no build, $@T is empty and makes `test -s $@T` fail.

Just dump the linker script with -fuse-ld=bfd.  lld since 15
(https://reviews.llvm.org/D124656) supports custom RELRO sections in the
GNU ld dumped linker script.

Reviewed-by: Sam James <sam@gentoo.org>