perf ui browser annotate: Don't show the source code view status initially

perf ui browser annotate: Don't show the source code view status initially

To avoid initial clutter, and not to change the view users that are not
interested in toggling the source code view, just show it when the user
does the first toggle keypress (pressing 's').

I know that there are users that really disable the source code view by
using:

  # perf config annotate.hide_src_code=yes

Tested-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/Z_TYux5fUg2pW-pF@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>