[gtk/matthiasc/for-master] testsuite: Fix a memory leak in the bitmask tests

[Matthias Clasen <matthiasc src gnome org>]

commit e6d8eedc00bb805fd82d25b1205ca9e13330ea44
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jul 8 16:34:58 2020 -0400

    testsuite: Fix a memory leak in the bitmask tests
    
    This was showing up when running under asan.

 testsuite/gtk/bitmask.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/testsuite/gtk/bitmask.c b/testsuite/gtk/bitmask.c
index 75aec409a7..167e729ea7 100644
--- a/testsuite/gtk/bitmask.c
+++ b/testsuite/gtk/bitmask.c
@@ -316,7 +316,13 @@ test_subtract_hardcoded (void)
               left_str++;
             }
 
-          g_test_message ("%s - %s\n", _gtk_bitmask_to_string (left), _gtk_bitmask_to_string (right));
+          {
+            char *sl = _gtk_bitmask_to_string (left);
+            char *sr = _gtk_bitmask_to_string (right);
+            g_test_message ("%s - %s\n", sl, sr);
+            g_free (sl);
+            g_free (sr);
+          }
           subtracted = _gtk_bitmask_subtract (_gtk_bitmask_copy (left), right);
 
           assert_cmpmasks (subtracted, expected);