patch 8.2.0984: not using previous window when closing a shell popup window

Problem:    Not using previous window when closing a shell popup window.
Solution:   Use "prevwin" if it was set. (closes #6267)
diff --git a/src/version.c b/src/version.c
index 7d7b965..91ae5ea 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    984,
+/**/
     983,
 /**/
     982,