Make ls-lisp.el behave like Posix hosts when directory doesn't exist

* lisp/ls-lisp.el (ls-lisp-insert-directory): For a directory
that cannot be accessed, signal an error, like insert-directory
does on Posix systems.  This causes files-tests.el to pass on
MS-Windows.
1 job for master in 51 minutes and 7 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #817
test-all

00:51:07

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:309: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:284: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1