patch 8.0.0942: using freed memory with ":terminal"

Problem:    Using freed memory with ":terminal" if an autocommand changes
            'shell' when splitting the window. (Marius Gedminas)
Solution:   Make a copy of 'shell'. (closes #1974)
diff --git a/src/version.c b/src/version.c
index d4617b0..263b004 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    942,
+/**/
     941,
 /**/
     940,