patch 8.2.1787: crash with 'incsearch' and very long line

Problem:    Crash with 'incsearch' and very long line.
Solution:   Check whether regprog becomes NULL. (closes #7063)
diff --git a/src/version.c b/src/version.c
index 7f528b9..877d63d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1787,
+/**/
     1786,
 /**/
     1785,