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/ex_docmd.c b/src/ex_docmd.c
index d0df1fd..13d5fe4 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -10890,6 +10890,9 @@
 		result = strbuf;
 		break;
 #endif
+	default:
+		result = (char_u *)""; /* avoid gcc warning */
+		break;
 	}
 
 	resultlen = (int)STRLEN(result);	/* length of new string */
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,