Restrict support to architecture independent packages

Since this fork is intended for building Debian packages containing
Java bytecode, shell scripts, etc., it is now hard-coded to generate
architecture independent packages.

So use -A to specify a binary-only build, limited to architecture
independent packages and remove shared library dependencies (since
architecture independent packages contain no native executables).

Specify packaging compatibility version.

Avoid directory name checks during debuild.

Fix build warnings