tools build: Move tabs to spaces where suitable

We've been hit several times by a Makefile bug where line indented by
tab was falsely considered as target command.

We prevent this by always using space indentation for everything except
for the target commands.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1480884178-8072-3-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>