To make it more apparent that there is not change in functionality we introduced
Makefile.parallel separately and now flip it with the main Makefile, which
moves into Makefile.perf.

The renames are:

   Makefile.parallel => Makefile
   Makefile          => Makefile.perf

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-igRfuw9ugbnnpixLd6wpptzl@git.kernel.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>