perf annotate: Split branch stack cycles information out of 'struct annotation_line'

The cycles info is used only when branch stack is provided.  Separate
them from 'struct annotation_line' into a separate struct and lazy
allocate them to save some memory.

Committer notes:

Make annotation__compute_ipc() check if the lazy allocation works,
bailing out if so, its callers already do error checking and
propagation.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231103191907.54531-2-namhyung@kernel.org


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