CLEANUP: config: use free_args() to release args array in cfg_eval_condition()

Doing so is cleaner than open-coding it and will support future extensions.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 5e21467..a1b9a47 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -1827,11 +1827,8 @@
 	if (errptr)
 		*errptr = args[0];
  done:
-	for (nbargs = 0; argp && argp[nbargs].type != ARGT_STOP; nbargs++) {
-		if (argp[nbargs].type == ARGT_STR)
-			free(argp[nbargs].data.str.area);
-	}
-	free(argp);
+	free_args(argp);
+	ha_free(&argp);
 	return ret;
 }