patch 8.1.2358: tests fail on Cirrus CI for FreeBSD

Problem:    Tests fail on Cirrus CI for FreeBSD.
Solution:   Fix a test and skip some. (Christian Brabandt, closes #5281)
diff --git a/src/testdir/test_source_utf8.vim b/src/testdir/test_source_utf8.vim
index e93ea29..99cb09c 100644
--- a/src/testdir/test_source_utf8.vim
+++ b/src/testdir/test_source_utf8.vim
@@ -1,7 +1,10 @@
 " Test the :source! command
+source check.vim
 
 func Test_source_utf8()
   " check that sourcing a script with 0x80 as second byte works
+  " does not work correctly on BSD
+  CheckNotBSD
   new
   call setline(1, [':%s/àx/--à1234--/g', ':%s/Àx/--À1234--/g'])
   write! Xscript
@@ -31,6 +34,7 @@
 
 " Test for sourcing a file with CTRL-V's at the end of the line
 func Test_source_ctrl_v()
+    CheckNotBSD
     call writefile(['map __1 afirst',
 		\ 'map __2 asecond',
 		\ 'map __3 athird',