rules.mak: Don't extract libs from .mo-libs in link command

rules.mak: Don't extract libs from .mo-libs in link command

For module build, .mo objects are passed to LINK and consumed in
process-archive-undefs. The reason behind that is documented in the
comment above process-archive-undefs.

Similarly, extract-libs should be called with .mo filtered out too.
Otherwise, the .mo-libs are added to the link command incorrectly,
spoiling the purpose of modularization.

Currently we don't have any .mo-libs usage, but it will be used soon
when we modularize more multi-source objects, like sdl and gtk.

Reported-by: Colin Lord <clord@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <1469600777-30413-2-git-send-email-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>