ls: fix a test failure that should have been skipped

* tests/ls/readdir-mountpoint-inode: Check to see if skip_test_ is
called in a helper function via $() instead of mistakenly failing.
* THANKS: Update.

THANKS

@@ -131,6 +131,7 @@ Cyril Bouthors                      cyril@bouthors.org
 Dale Scheetz                        dwarf@polaris.net
 Dameon G. Rogers                    dgr03@uark.edu
 Dan Hagerty                         hag@gnu.ai.it.edu
+Dan Hipschman                       dsh@linux.ucla.edu
 Dan Jacobson                        jidanni@jidanni.org
 Dan Pascu                           dan@services.iiruc.ro
 Daniel Bergstrom                    noa@melody.se

tests/ls/readdir-mountpoint-inode

@@ -64,6 +64,7 @@ inode_via_readdir()
 
 for dir in $mount_points; do
   readdir_inode=$(inode_via_readdir $dir)
+  test $? = 77 && continue
   stat_inode=$(env stat --format=%i $dir)
   # If stat fails or says the inode is 0, skip $dir.
   case $stat_inode in 0|'') continue;; esac