perf report: Support a new key to reload the browser

Sometimes we may need to reload the browser to update the output since
some options are changed.

This patch creates a new key K_RELOAD. Once the __cmd_report() returns
K_RELOAD, it would repeat the whole process, such as, read samples from
data file, sort the data and display in the browser.

 v5:
 ---
 1. Fix the 'make NO_SLANG=1' error. Define K_RELOAD in util/hist.h.
 2. Skip setup_sorting() in repeat path if last key is K_RELOAD.

 v4:
 ---
 Need to quit in perf_evsel_menu__run if key is K_RELOAD.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200220013616.19916-3-yao.jin@linux.intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>