implemented method add_checker for CheckInfo in bitboard::checkinfo.rs

engine/src/bitboard/checkinfo.rs

@@ -12,4 +12,10 @@ impl CheckInfo {
       move_mask: 0xFFFF_FFFF_FFFF_FFFF
     }
   }
+
+  #[inline(always)]
+  pub fn add_checker(&mut self, move_mask: u64) {
+    self.move_mask &= move_mask;
+    self.check_count += 1;
+  }
 }