perf annotate: Move offsets array from 'struct annotation' to 'struct annotated_source'

perf annotate: Move offsets array from 'struct annotation' to 'struct annotated_source'

The offsets array keeps pointers to 'struct annotation_line' entries
which are available in the 'struct annotated_source'.  Let's move it to
there.

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231103191907.54531-6-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>