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 <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/session.c

···
 	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;
 	}
 
···
 		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;
 	}