Remove variable tracing_paths and check in pathtrace_match

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/defs.h b/defs.h
index 1d607c7..ca5d088 100644
--- a/defs.h
+++ b/defs.h
@@ -523,7 +523,9 @@
 extern bool qflag;
 extern bool not_failing_only;
 extern bool show_fd_path;
-extern bool tracing_paths;
+/* are we filtering traces based on paths? */
+extern const char **paths_selected;
+#define tracing_paths (paths_selected != NULL)
 extern bool need_fork_exec_workarounds;
 extern unsigned xflag;
 extern unsigned followfork;