perf build: Use feature dump file for build-test

To prevent the feature check tests to run repeately, one time per
'tests/make' target/test, this patch utilizes the previously introduced
'feature-dump' make target and FEATURES_DUMP variable, making sure that
the feature checkers run only once when doing build-test for normal test
cases.

However, since standard users doesn't reuse features dump result, we'd
better give an option to check their behaviors. The above feature
should be used to make build-test faster only. Only utilize it for
build-test.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1454068269-235999-1-git-send-email-wangnan0@huawei.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>