I've merged and pushed all my changes, the build finishes and the regular + autopkgtests pass.
TODO:
1. Send more patches upstream
2. Review the following patches and see if we can eliminate even more code copies:
#use_packaged_vcflib # 1.0.0+dfsg-1 is incompatible with the bundled htslib
#use_packaged_htslib # waiting on
https://github.com/samtools/htslib/pull/904/files or similiar to be merged & new htslib release
#use_packaged_vw # debian package is out of date, missing array_parameters.h, and not in testing/stable
#use_packaged_sdsl # fails many tests, local copy is a newer snapshot than Debian's
#use_packaged_protobuf ?