dabba: rename files to fit file convention.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: rename "sock_filter" refs to "sock-filter"

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabbad: refactor sock filter function names.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabbad: add sock fprog to pbuf sock fprog converter.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabba: check socket filter presence from its length.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>
dabbad: don't parse/attach zero-length sock filters.

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>