'make build-test' is painful because of time consuming. In a full test,
all test cases are built twice with tools/perf/Makefile and
tools/perf/Makefile.perf. 'Makefile' automatically computes parallel
options for make, but 'Makefile.perf' not, so all test cases is built
with one job. It is very slow.

This patch adds '-j' options to Makefile.perf testing. It computes
parallel building options like what tools/perf/Makefile does, and pass
'-j' option to Makefile.perf test.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1452687442-6186-2-git-send-email-wangnan0@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>