check-style should recommend use of g_slice

tools/check-style

@@ -48,6 +48,7 @@ violations = [
      |getpwnam|getpwuid|gmtime|localtime \
      |rand|readdir|strtok|ttyname', 'Not thread-safe posix, use _r variant'],
     ['while.*g_list_nth', 'Use g_list_next() instead of g_list_nth'],
+    ['[^a-z]g_new.*1[^0-9]', 'Use g_slice_new() instead of g_new()'],
 ]
 # No validation for strings, comments, includes
 omissions = [