perft-test: improve displayed info, add selective tests

- print total #tests, #tests to do and VERSION string
- add starting point for tests, and #tests to run

test/common-test.h

@@ -451,7 +451,12 @@ struct fentest {
 
 static int fentest_cur = -1;
 
-static char *next_fen(uint module)
+static __unused void restart_fen(void)
+{
+    fentest_cur = -1;
+}
+
+static __unused char *next_fen(uint module)
 {
     fentest_cur++;