patch 8.1.1154: getting a newer msgfmt on Travis is too complicated

Problem:    Getting a newer msgfmt on Travis is too complicated.
Solution:   Use a "sourcline" entry. (Ozaki Kiichi, closes #4236)
diff --git a/src/version.c b/src/version.c
index a25944d..022fc43 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1154,
+/**/
     1153,
 /**/
     1152,