ssvnc fails to cross build from source for two distinct reasons. The
immediate failure arises from not passing cross tools to make. A
required dependency is not found as it is only requested for the host
architecture, but make defaults to using build architecture build tools.
Using dh_auto_build is the easiest way to fix this. Then, running the
host's java compiler fails. For using the compiler, a native Java
development kit is needed. The attached patch addresses both issues.
Please consider applying it.

Helmut