perf hists: Exchange order of comparing items when collapsing hists

When comparing entries for collapsing put the given entry first, and
then the iterated entry.  This is not the case of hist_entry__cmp() when
called if given sort keys don't require collapsing.  So change the order
for the sake of consistency.  It will be required for matching and/or
linking multiple hist entries.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1355128197-18193-2-git-send-email-namhyung@kernel.org


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