Fix rts/packages.conf.in ld-options for clang.

Technically, '-u' is an ld option, not a compiler option,
and clang considers this argument unused. Hence, we must
explicitly forward this to the linker.

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Untabify rts/packages.conf.in

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Actually fix rts/packages.conf.in ld-options.

Signed-off-by: Austin Seipp <aseipp@pobox.com>