perf tools: Move start conditions to start of the flex file

Moving start conditions to start of the flex file so it's clear what the
INITIAL condition rules are.

Plus adding default rule for INITIAL condition. This prevents default
space to be printed for events like:

$ ./perf stat -e "cycles        " kill 2>/dev/null
        $
^^^^^^^^

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1380299398-10839-1-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>