patch 8.1.0936: may leak memory when using 'vartabstop'

Problem:    May leak memory when using 'vartabstop'. (Kuang-che Wu)
Solution:   Fix handling allocated memory for 'vartabstop'. (closes #3976)
diff --git a/src/version.c b/src/version.c
index 8dd86f0..81bafe5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    936,
+/**/
     935,
 /**/
     934,