perf report: Add a simple GTK2-based 'perf report' browser

This patch adds a simple GTK2-based browser to 'perf report' that's
based on the TTY-based browser in builtin-report.c.

To launch "perf report" using the new GTK interface just type:

  $ perf report --gtk

The interface is somewhat limited in features at the moment:

  - No callgraph support

  - No KVM guest profiling support

  - No color coding for percentages

  - No sorting from the UI

  - ..and many, many more!

That said, I think this patch a reasonable start to build future features on.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202231952410.6689@tux.localdomain


[ committer note: Added #pragma to make gtk no strict prototype problem go
  away as suggested by Colin Walters modulo avoiding push/pop ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>