perf ui: Add gtk2 support into setup_browser()

perf ui: Add gtk2 support into setup_browser()

Now setup_browser can handle gtk2 front-end so split the TUI code to
ui/tui/setup.c in order to remove dependency.

To this end, make ui__init/exit global symbols and take an argument.
Also split gtk code to ui/gtk/setup.c.

Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1335761711-31403-5-git-send-email-namhyung.kim@lge.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>