patch 9.0.0260: using freed memory when using 'quickfixtextfunc' recursively

Problem:    Using freed memory when using 'quickfixtextfunc' recursively.
Solution:   Do not allow for recursion.
diff --git a/src/version.c b/src/version.c
index b1943bb..02c20f0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -732,6 +732,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    260,
+/**/
     259,
 /**/
     258,