elements/base/zip.bst: use buildflags from environment
Currently 'zip' doesn't use our buildflags which means it doesn't enable our optimizations or hardening.
We have to avoid calling 'configure' script directly which is supposed to be called from 'Makefile' instead, otherwise our params will be lost.
We have to switch to different 'make' targets in order to make all our buildflags effective.
Part of #317 (closed)