perf annotate: Add support to toggle percent type

Add new key bindings to toggle percent type/base in annotation UI browser:

 'p' to switch between local and global percent type
 'b' to switch between hits and perdio percent base

Add the following help messages to the UI browser '?' window:

  ...
  p             Toggle percent type [local/global]
  b             Toggle percent base [period/hits]
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-17-jolsa@kernel.org


[ Moved percent_type to be the last arg to sym_title(), its an arg to what is being formmated (buf, size) ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>