_filedir_xspec: Fix with failglob on
lvm: _lvm_count_args parameter must be quoted in order to failglob not to complain
(testsuite) Add vgcreate test case for _lvm_count_args with failglob on
_lvm: using a single-pattern case and invoking function according to words[1]
umount: Fix mount points escaping/unescaping with Bash-4.3
(testsuite): move testing of _linux_fstab() to umount.exp

The function is only used for umount completion.
_parse_help: Fix failglob failures (Alioth: #314707)