perf build: Separate feature make support into config/Makefile.feature

perf build: Separate feature make support into config/Makefile.feature

Move feature related code into separate makefile. The new
Makefile.feature is included from config/Makefile. It will be moved
later into tools/build.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-kj76wphg05x83n6d5ff85ybx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>