tools: genext2fs: add support for blocksize != 1024

tools: genext2fs: add support for blocksize != 1024

This patch series is extracted from
http://ftp.de.debian.org/debian/pool/main/g/genext2fs/genext2fs_1.4.1-4.debian.tar.gz

The patches are used in Debian for quite a long time, so I assume that
this is solid material. At least, my Ubuntu host fsck.ext4 does not bark :-)

The goal is to allow building filesystems with larger blocksizes instead of the
current default of 1k. This should improve performance and lifetime when the
filesystem is stored e.g. on a SD card (on Raspberry Pi/I2SE Duckbill for example)
which uses internal flash memory. Writing to flash memory is slow because writing
the data of one block results in erasing a whole erase block of the flash memory.
Thus it is preferable to align the filesystem block size on a flash device with
the erase blocksize, or at least bring it closer to the later one, to avoid
unnecessary write amplification.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40921 3c298f89-4303-0410-b956-a3cf2f4a3e73