Revert "use code generation for GITCOMMIT/VERSION too"

This reverts commit 85744a35de0e30c2dd6741b833f38ff218c8a3fc.

Conflicts:
	.gitignore
	hack/make.sh

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)