Store cacheline related entries in nested hist object for each cacheline
data. Nested entries are sorted by 'offset' within related cacheline.

We will allow specific sort keys to be configured for nested cacheline
data entries in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Joe Mario <jmario@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1474558645-19956-18-git-send-email-jolsa@kernel.org
[ he__get_hists() should return NULL when c2c_hists__init() fails ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>