perf tools: Support static linking with libdw

perf tools: Support static linking with libdw

The Fedora 22 version of libdw requires a couple of extra libraries to
link. With a dynamic link the dependencies are pulled in automatically,
but this doesn't work for static linking. Add the needed libraries
explicitely to the feature probe and the Makefile.

v2: Explicitly check for static linking and only add the dependencies
    when -static is set. This is to avoid regressions on Arnaldo's system.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1439419717-20601-1-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>