block-extroot, block-mount: Fixed multiple bugs which prevented e2fsck from being...

block-extroot, block-mount: Fixed multiple bugs which prevented e2fsck from being executed on the external root filesystem before mounting it as root.  Added /etc/e2fsck.conf which indicates that the clock is broken (since most OpenWRT devices don't have a battery backed RTC) so that e2fsck will not exit with fatal error when the rdat has not yet been run (i.e. before network).

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@22002 3c298f89-4303-0410-b956-a3cf2f4a3e73