patch 8.2.3662: illegal memory access if malloc() fails

Problem:    Illegal memory access if malloc() fails.
Solution:   Check 'foldmethod' is not empty. (closes #9207)
diff --git a/src/version.c b/src/version.c
index 1a39190..58a1856 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3662,
+/**/
     3661,
 /**/
     3660,