patch 8.0.0780: build failure on Travis

Problem:    Build failure on Travis.
Solution:   Set distribution explicitly. Use Lua and Ruby dev. (Ken Takata,
            closes #1884)
diff --git a/src/version.c b/src/version.c
index 1654ee3..ddac62f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    780,
+/**/
     779,
 /**/
     778,