zdbsp fails to cross build from source, because it confuses build vs
host. Refer to man dpkg-architecture for more information. The attached
patch makes zdbsp cross buildable. Please consider applying it.
Thanks for the report, and the patch. It looks good to me, but as
we are in hard freeze for Buster and this (sadly) would not qualify
for a freeze exception, I'm going to wait before applying it or
uploading a fixed package to sid.