perf tools: Add support to specify hw event as PMU event term

Add a way to specify hw event as PMU event term like:

 'cpu/event=cpu-cycles/u'
 'cpu/event=instructions,.../u'
 'cpu/cycles,.../u'

The 'event=cpu-cycles' term is replaced/translated by the hw events
term translation, which is exposed by sysfs 'events' group attribute.

Add parser bits, the rest is already handled by the PMU alias code.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349873598-12583-8-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>