patch 8.0.0598: building with gcc 7.1 yields new warnings

Problem:    Building with gcc 7.1 yields new warnings.
Solution:   Initialize result. (John Marriott)
diff --git a/src/version.c b/src/version.c
index dd39fcd..700b4bd 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    598,
+/**/
     597,
 /**/
     596,