Hello Andrey,
$(MAKE) clear (as a replacement for $(MAKE) clean) should run in override_dh_auto_clean, not override_dh_clean.
Done.
debian/watch is empty
Filled in.
There is a commented out override_dh_auto_configure.
Removed.
002-add-fortify-flags.patch adds -D_FORTIFY_SOURCE=2 explicitly, but the proper fix is making the upstream build system respect the compile flags set by dpkg-buildflags.
Removed the patch. Instead, export CXXFLAGS from debian/rules. Thanks, Alan