perf top: Always sample time to satisfy needs of use of ordered queuing

mainline inclusion
from mainline-5.1-rc6
commit 1e6db2ee86e6a4399fc0ae5689e55e0fd1c43caf
category: bugfix
bugzilla: NA
CVE: NA

-------------------------------------------------
Bastian reported broken 'perf top -p PID' command, it won't display any
data.

The problem is that for -p option we monitor single thread, so we don't
enable time in samples, because it's not needed.

However since commit 16c66bc167cc we use ordered queues to stash data
plus later commits added logic for dropping samples in case there's big
load and we don't keep up. All this needs timestamp for sample. Enabling
it unconditionally for perf top.
Reported-by: NBastian Beischer <bastian.beischer@rwth-aachen.de>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bastian beischer <bastian.beischer@rwth-aachen.de>
Fixes: 16c66bc167cc ("perf top: Add processing thread")
Link: http://lkml.kernel.org/r/20190415125333.27160-1-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NChunmei Xu <xuchunmei@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

tools/perf/builtin-top.c

@@ -1371,6 +1371,7 @@ int cmd_top(int argc, const char **argv)
 			 * */
 			.overwrite	= 0,
 			.sample_time	= true,
+			.sample_time_set = true,
 		},
 		.max_stack	     = sysctl__max_stack(),
 		.annotation_opts     = annotation__default_options,