deb: fix "non-empty-dependency_libs-in-la-file" lintian error

[groonga-dev,01930]

Patch by Hideki Yamane. Thanks!!!
deb: enable hardening features

see https://wiki.debian.org/Hardening

[groonga-dev,01930]

Patch by Hideki Yamane. Thanks!!!
deb: fix missing-pre-dependency-on-multiarch-support lintian error

[groonga-dev,01930]

Patch by Hideki Yamane. Thanks!!!