Remove unused variable from crc32()
Initialize the bitmap for every file system

Some file systems only use pc_set_bit() (ie they do not call pc_clear_bit())
when they build the bitmap of blocks in use. In these case it is important
to clear the bitmap first.

Signed-off-by: Patryck Rouleau <pfrouleau@gmail.com>
Ignore files generated by automake and autoheader