Unlink temp file after blockfile tests

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Allow multiple colormaps in blockfiles

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Correctly check mmap return value

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Use byte offset when mapping new colormaps

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Test multi-colormap blockfiles

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Make blockfile magic 15 bytes long

We're planning a "journal" area that will be 17 bytes long, so between the two
we'll be on an 8-byte boundary at the end of the magic.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Add a CRC-64 implementation

We're using the ECMA-182 polynomial. This will let us add some verification to
block files.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>