perf tools: Makefile: Use $(QUIET_GEN) for perf.so

So that we get this:

    CC /home/acme/git/build/perf/bench/mem-memcpy-x86-64-asm.o
    GEN perf-archive
*   GEN /home/acme/git/build/perf/python/perf.so
    CC /home/acme/git/build/perf/builtin-annotate.o

Instead of silently building the python binding.

LKML-Reference: <1296890359-22659-1-git-send-email-mfwitten@gmail.com>
Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>