debian/rules: Add a comment explaining why we do weird test things.

[catacomb] / debian / rules

#! /usr/bin/make -f
%:; dh $@ --parallel -Bdebian/build

## Test both with and without CPU-specific optimizations.
override_dh_auto_test:
        dh_auto_test --parallel -Bdebian/build
        CATACOMB_CPUFEAT="-*" dh_auto_test --parallel -Bdebian/build