perf test: Keep test result clean if '-v' not set

According to [1], 'perf test' should avoid output too much information
if '-v' is not set, only 'Ok', 'FAIL' or 'Skip' need to be printed.

This patch removes several messages sent directly to stderr to make
the output clean.

Before this patch:

  # perf test dummy
  23: Test using a dummy software event to keep tracking       : (not supported) Ok

After this patch:

  # perf test dummy
  23: Test using a dummy software event to keep tracking       : Skip

[1] http://lkml.kernel.org/r/20151020134155.GE4400@redhat.com

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446547486-229499-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index 52d5597..512d362 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -36,7 +36,7 @@
 static int test__bpf_parsing(void *obj_buf __maybe_unused,
 			     size_t obj_buf_sz __maybe_unused)
 {
-	fprintf(stderr, " (skip bpf parsing)");
+	pr_debug("Skip bpf parsing\n");
 	return 0;
 }
 #endif
@@ -55,7 +55,7 @@
 	 * and clang is not found in $PATH, and this is not perf test -v
 	 */
 	if (verbose == 0 && !llvm_param.user_set_param && llvm__search_clang()) {
-		fprintf(stderr, " (no clang, try 'perf test -v LLVM')");
+		pr_debug("No clang and no verbosive, skip this test\n");
 		return TEST_SKIP;
 	}
 
@@ -86,11 +86,8 @@
 	err = llvm__compile_bpf("-", &obj_buf, &obj_buf_sz);
 
 	verbose = old_verbose;
-	if (err) {
-		if (!verbose)
-			fprintf(stderr, " (use -v to see error message)");
-		return -1;
-	}
+	if (err)
+		return TEST_FAIL;
 
 	err = test__bpf_parsing(obj_buf, obj_buf_sz);
 	free(obj_buf);