patch 8.2.3599: not all gdbinit files are recognized

Problem:    Not all gdbinit files are recognized.
Solution:   Add "gdbinit". (Doug Kearns)
diff --git a/src/version.c b/src/version.c
index 7cffc01..cb1599d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -758,6 +758,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3599,
+/**/
     3598,
 /**/
     3597,