patch 8.0.1677: no compiler warning for wrong format in vim_snprintf()

Problem:    No compiler warning for wrong format in vim_snprintf().
Solution:   Add printf attribute for gcc.  Fix reported problems.
diff --git a/src/version.c b/src/version.c
index 4ee3c25..1b2a1fa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1677,
+/**/
     1676,
 /**/
     1675,