patch 8.1.1551: warning for shadowing popup_dragwin

Problem:    Warning for shadowing popup_dragwin. (Dominique Pelle)
Solution:   Add missing change.
diff --git a/src/ui.c b/src/ui.c
index 9e387b4..db878e6 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -2929,7 +2929,6 @@
 #endif
 #ifdef FEAT_TEXT_PROP
     static int   in_popup_win = FALSE;
-    static win_T *popup_dragwin = NULL;
 #endif
     static int	prev_row = -1;
     static int	prev_col = -1;
diff --git a/src/version.c b/src/version.c
index 96670c6..b213bda 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1551,
+/**/
     1550,
 /**/
     1549,