patch 8.1.0878: test for has('bsd') fails on some BSD systems

Problem:    Test for has('bsd') fails on some BSD systems.
Solution:   Adjust the uname match. (James McCoy, closes #3909)
diff --git a/src/version.c b/src/version.c
index 3ad7869..6a8ba37 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    878,
+/**/
     877,
 /**/
     876,