For nmount(), allow a text string error message to be propagated back to user-space if a parameter named "errmsg" is passed into the iovec. Used in conjunction with vfs_mount_error(), more useful error messages than errno can be passed back to userspace when mounting a filesystem fails.
For nmount(), allow a text string error message to be propagated back
to user-space if a parameter named "errmsg" is passed into the iovec.
Used in conjunction with vfs_mount_error(), more useful error messages
than errno can be passed back to userspace when mounting a filesystem
fails.

Discussed with:		phk, pjd

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