patch 8.1.0249: GTK: when screen DPI changes Vim does not handle it

Problem:    GTK: when screen DPI changes Vim does not handle it.
Solution:   Handle the gtk-xft-dpi signal. (Roel van de Kraats,
            closes #2357)
diff --git a/src/version.c b/src/version.c
index cc1648f..bb730f4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    249,
+/**/
     248,
 /**/
     247,