patch 8.2.0327: crash when opening and closing two popup terminal windows

Problem:    Crash when opening and closing two popup terminal windows.
Solution:   Check that prevwin is valid. (closes #5707)
diff --git a/src/version.c b/src/version.c
index ad27946..693a1d6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    327,
+/**/
     326,
 /**/
     325,