fstab with UUID or LABEL: boot stops and goes into sulogin if device absent, no support for nofail option

[az143]

i found this small issue with 4.8: if you have a fstab'd filesystem on a device that isn't always present, e.g. sd card or usb stick, and which is identified by LABEL= or UUID= in fstab, then 4.8 doesn't boot if the device happens to be absent. finit doesn't deal with the 'nofail' mount option, which should make mount (and fsck) ignore absence errors.

4.7 boots fine with that setup, but that's likely due to bug #400. if your filesystem is listed by block device then both finit versions already work fine, because in that case the presence of the block device file is (checkable and) checked before the fsck invocation. it's just the indirect LABEL'd devices that cause trouble.

i've patched this by making fsck not bail out on error if hasmntopt() indicates 'nofail' was set. the patch is just a few lines, and i'll provide a pull request in a few minutes.