perf hists browser: Override ui_browser refresh_dimensions method

perf hists browser: Override ui_browser refresh_dimensions method

This requires some more work so that we can really just use the width of
current entries when we want to partition the screen.

Right now its just a prep patch so that we can have where to update
ui_browser->rows when introducing the column headers line, that will be
togglable, so we need to update it everytime we refresh the dimensions
of the browser.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
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-ovk654rx525b4657y0mh6ku9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>