* guix/build/ant-build-system.scm (default-build.xml): Generate default manifest. (strip-jar-timestamps): Repack jar archive with zip.
* guix/build-system/ant.scm: New file. * guix/build/ant-build-system: New file. * Makefile.am (MODULES): Add new files. * doc/guix.texi (Build Systems): Document ant-build-system.