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_quickfix.vim b/src/testdir/test_quickfix.vim
index 3a9e672..d31650f 100644
--- a/src/testdir/test_quickfix.vim
+++ b/src/testdir/test_quickfix.vim
@@ -1685,6 +1685,7 @@
 endfunc
 
 func Test_switchbuf()
+  CheckNotBSD
   call s:create_test_file('Xqftestfile1')
   call s:create_test_file('Xqftestfile2')
   call s:create_test_file('Xqftestfile3')