perf tools: Reconstruct event with modifiers from perf_event_attr

perf tools: Reconstruct event with modifiers from perf_event_attr

The modifiers:

  k		kernel space
  u		user space
  h		hypervisor
  G		guest
  H		host
  p, pp, ppp    precision level (PEBS)

that can be suffixed to an event were lost when tools used event_name()
to reconstruct them from the perf_event_attr entries in a perf.data
file.

Fix it by following the defaults used for these modifiers in the current
codebase, so:

 $ perf record -e instructions:u usleep 1 2> /dev/null
 $ perf evlist
 instructions:u
 $ perf record -e cycles:k usleep 1 2> /dev/null
 $ perf evlist
 cycles:k
 $ perf record -e cycles:kh usleep 1 2> /dev/null
 $ perf evlist
 cycles:kh
 $ perf record -e cache-misses:G usleep 1 2> /dev/null
 $ perf evlist
 cache-misses:G
 $ perf record -e cycles:ppk usleep 1 2> /dev/null
 $ perf evlist
 cycles:kpp
 $

Also works with 'top', 'report', etc.

More work needed to cover tracepoints and software events while not
dragging lots of baggage to the python binding, this is a minimal fix
for v3.5.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-4hl5glle0hxlklw4usva1mkt@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>