perf report: Don't show blank lines if entry has no callchain

When all callchains of a hist entry is percent-limited, do not add a
blank line at the end.  It makes the entry look like it doesn't have
callchains.

Reported-and-Tested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20160128122454.GA27446@danjae.kornet
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>