patch 8.1.0682: text properties not adjusted when backspacing replaced text

Problem:    Text properties are not adjusted when backspacing replaced text.
Solution:   Keep text properties on text restored in replace mode.
diff --git a/src/globals.h b/src/globals.h
index d60968b..2a7ecd1 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1658,6 +1658,10 @@
 EXTERN int ctrl_break_was_pressed INIT(= FALSE);
 #endif
 
+#ifdef FEAT_TEXT_PROP
+EXTERN int text_prop_frozen INIT(= 0);
+#endif
+
 /*
  * Optional Farsi support.  Include it here, so EXTERN and INIT are defined.
  */