patch 8.2.4684: cannot open a channel on a Unix domain socket

Problem:    Cannot open a channel on a Unix domain socket.
Solution:   Add Unix domain socket support. (closes #10062)
diff --git a/src/testdir/check.vim b/src/testdir/check.vim
index 55a64bd..aff0918 100644
--- a/src/testdir/check.vim
+++ b/src/testdir/check.vim
@@ -95,7 +95,7 @@
   endif
 endfunc
 
-" Command to check for running on Linix
+" Command to check for running on Linux
 command CheckLinux call CheckLinux()
 func CheckLinux()
   if !has('linux')