Use the per-feature check flags for the unwinding feature in order to
correctly compile the test-all, libunwind and libunwind-debug-frame
feature checks.

Tested on x86_64, ARMv7 and ARMv8 with and without LIBUNWIND_DIR set in
'make -C tools/perf'
Signed-off-by: NJean Pihet <jean.pihet@linaro.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NJiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: patches@linaro.org
Link: http://lkml.kernel.org/r/1386678244-13535-3-git-send-email-jean.pihet@linaro.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>