perf session: Add missing newlines to some pr_err() calls

Before:

  [acme@zoo linux]$ perf evlist
  WARNING: The perf.data file's data size field is 0 which is unexpected.
  Was the 'perf record' command properly terminated?
  non matching sample_type[acme@zoo linux]$

After:

  [acme@zoo linux]$ perf evlist
  WARNING: The perf.data file's data size field is 0 which is unexpected.
  Was the 'perf record' command properly terminated?
  non matching sample_type
  [acme@zoo linux]$

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-wscok3a2s7yrj8156oc2r6qe@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -29,7 +29,7 @@ static int perf_session__open(struct perf_session *session)
 	struct perf_data_file *file = session->file;
 
 	if (perf_session__read_header(session) < 0) {
-		pr_err("incompatible file format (rerun with -v to learn more)");
+		pr_err("incompatible file format (rerun with -v to learn more)\n");
 		return -1;
 	}
 
@@ -37,17 +37,17 @@ static int perf_session__open(struct perf_session *session)
 		return 0;
 
 	if (!perf_evlist__valid_sample_type(session->evlist)) {
-		pr_err("non matching sample_type");
+		pr_err("non matching sample_type\n");
 		return -1;
 	}
 
 	if (!perf_evlist__valid_sample_id_all(session->evlist)) {
-		pr_err("non matching sample_id_all");
+		pr_err("non matching sample_id_all\n");
 		return -1;
 	}
 
 	if (!perf_evlist__valid_read_format(session->evlist)) {
-		pr_err("non matching read_format");
+		pr_err("non matching read_format\n");
 		return -1;
 	}