checker: no longer allow automatic dereferncing in a = b

vlib/builtin/builtin_nix.c.v

@@ -131,7 +131,7 @@ fn break_if_debugger_attached() {
 	unsafe {
 		mut ptr := &voidptr(0)
 		*ptr = voidptr(0)
-		_ = ptr
+		//_ = ptr
 	}
 }