* guix/build/maven/pom.scm (fix-pom-dependencies): Support fixing
modules that do not exist.
* guix/build/maven-build-system.scm (fix-pom): Fix modules.
* guix/build/maven-build-system (fix-pom): Fix a single pom file without
recursing
(fix-pom-files): Find local packages and all submodules, and fix them
all at once.
(add-local-package): Move to...
* guix/build/maven/pom.scm (add-local-package): ...here.
(pom-and-submodules, pom-local-packages): New procedures.
* guix/build/maven/pom.scm (pom-version, pom-groupid): Do not use inputs
and local packages information anymore. Adapt file to new arguments.
* guix/build/maven-build-system.scm: Adapt to new arguments.
* guix/build/java-utils.scm: Adapt to new arguments.
* guix/build/maven/java.scm: New file.
* guix/build/maven/plugin.scm: New file.
* guix/build/maven/pom.scm: New file.
* Makefile.am (MODULES): Add them.
* guix/build-system/ant.scm (%ant-build-system-modules): Add them to the
build side.
* guix/build/java-utils.scm (generate-plugin.xml, install-pom-file)
(install-from-pom): New procedures.
