patch 8.2.1487: Travis: installing snd-dummy is not always useful

Problem:    Travis: installing snd-dummy is not always useful.
Solution:   Only install snd-dummy on amd64. (Ozaki Kiichi, closes #6738)
diff --git a/src/version.c b/src/version.c
index 8c98eb4..51b87ce 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1487,
+/**/
     1486,
 /**/
     1485,