patch 8.1.0626: MS-Windows: no resize to fit parent when using --windowid

Problem:    MS-Windows: no resize to fit parent when using --windowid.
Solution:   Pass FALSE for "mustset" in gui_set_shellsize(). (Agorgianitis
            Loukas, closes #3616)
diff --git a/src/version.c b/src/version.c
index 594be52..4d39dde 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    626,
+/**/
     625,
 /**/
     624,