buici-clock fails to cross build from source. The immediate failure goes
like this: The packaging configures via dh_auto_configure, which passes
--host to the toplevel configure. That configure calls xo/configure
without --host and configures for the build architecture there. When
building, it misses out dependencies that are only present for the host
architecture.

The solution here is to pass down the --host flag to the nested
configure. The ideal solution would be to use AC_CONFIG_SUBDIRS, but I
couldn't make that work here. Instead, I propose explicitly passing
--build and --host down.

Nextup, Makefile.in hard codes the build architecture pkg-config. That's
bad. Detecting cairo should be done at configure time. The recommended
way for doing so is using PKG_CHECK_MODULES.

I'm attaching a patch that fixes both issues. Since the build does not
regenerate configure, you must do so manually after applying the patch.

Helmut