perf annotate browser: Change selection to struct annotation_line

Use struct annotation_line as a browser::selection.

We want to be able to use the annotate_browser for all sorts of source
data, so it needs to be able to work over the generic struct
annotation_line.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171106105617.GC20858@krava


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