patch 8.1.1480: desktop file check doesn't run on CI

Problem:    Desktop file check doesn't run on CI.
Solution:   Install the desktip-file-utils packages. (Christian Brabandt,
            closes #4498)
diff --git a/.travis.yml b/.travis.yml
index 1e5ee56..51d3578 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -86,6 +86,7 @@
       - tcl-dev
       - cscope
       - libgtk2.0-dev
+      - desktop-file-utils
   homebrew:
     packages:
       - lua
diff --git a/src/version.c b/src/version.c
index 947efb1..72f4009 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1480,
+/**/
     1479,
 /**/
     1478,