perf report: Fix histogram entry collapsing for -F option

perf report: Fix histogram entry collapsing for -F option

Users can use -F/--fields option to set output fields and sort keys
together.

But it missed to set perf_hpp_list->need_collapse for sort entries that
have se_collapse callbacks.

So it ends up with having duplicated entries separately.

For example, let's run this command first.

  $ perf mem record -t load -U -- perf test -w datasym

This will record samples for memory access (load) to struct 'buf' and a
loop condition ('sig_atomic_t') types.

So the following two commands should have identical output.

  $ perf report -s type --stdio --percent-limit=1 -q
      87.80%  perf                  buf
      12.17%  perf                  sig_atomic_t

But using -F option didn't collapse the entries based on types so the
result looked like below:

  $ perf report -F overhead,type --stdio --percent-limit=1 -q
      23.31%  perf                  buf
      22.84%  perf                  buf
      21.26%  perf                  buf
      20.39%  perf                  buf
      12.17%  perf                  sig_atomic_t

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>