rules.mak: remove $(sort) from extract-libs

Duplicate removal was added to extract-libs in order to avoid including
the same library multiple times into the linking command line; this could
potentially happen when using "foo.mo-libs" (which adds the library to
all components, causing it to appear N times if the module is composed
of N objects).  However, sorting and removing duplicates causes problems
with static linking, and also with space-separated linker options as
found in some Mac OS X packaging systems.  Furthermore, the "optimization"
is really a non-problem since we do not expect .mo modules to be composed
of many files.

Reported-by: Sean Bruno <sbruno@ignoranthack.me>
Tested-by: Sean Bruno <sbruno@ignoranthack.me>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1402929805-16836-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>