timevar: get rid of a useless macro

* lib/timevar.h (timevar_report): Rename as...
(timevar_enabled): this.
* lib/timevar.c (TIMEVAR_ENABLE): Remove.

src/main.c

@@ -80,7 +80,7 @@ main (int argc, char *argv[])
 
   getargs (argc, argv);
 
-  timevar_report = trace_flag & trace_time;
+  timevar_enabled = trace_flag & trace_time;
   timevar_init ();
   timevar_start (TV_TOTAL);