perf record: Put new line after target override warning

There's no new-line after target-override warning, now:

  $ perf record -a --per-thread
  Warning:
  SYSTEM/CPU switch overriding PER-THREAD^C[ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.705 MB perf.data (2939 samples) ]

with patch:

  $ perf record -a --per-thread
  Warning:
  SYSTEM/CPU switch overriding PER-THREAD
  ^C[ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.705 MB perf.data (2939 samples) ]
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 16ad2ffb ("perf tools: Introduce perf_target__strerror()")
Link: http://lkml.kernel.org/r/20180206181813.10943-3-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -1803,7 +1803,7 @@ int cmd_record(int argc, const char **argv)
 	err = target__validate(&rec->opts.target);
 	if (err) {
 		target__strerror(&rec->opts.target, err, errbuf, BUFSIZ);
-		ui__warning("%s", errbuf);
+		ui__warning("%s\n", errbuf);
 	}
 
 	err = target__parse_uid(&rec->opts.target);