patch 8.0.0235: memory leak in diff mode

Problem:    Memory leak detected when running tests for diff mode.
Solution:   Free p_extra_free.
diff --git a/src/version.c b/src/version.c
index 8622e6d..65208d0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    235,
+/**/
     234,
 /**/
     233,