perf report: Fix sort__sym_cmp to also compare end of symbol

When using a map file from a JIT, due to memory reuse, we can obtain
multiple symbols with the same start address but a different length.

The symbols__find does check for the end so not doing it in
sort__sym_cmp was causing the hist_entry in the annotate part of a
report to match to the wrong entry, causing a fatal error.

Signed-off-by: Yannick Brosseau <scientist@fb.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/1434584470-17771-1-git-send-email-scientist@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>