* guix/build-system/cmake.scm (cmake-build): Change 'out-of-source?' to default to #t. * guix/build/cmake-build-system.scm (configure): Add 'out-of-source?' keyword parameter and honor it.
* guix/build/cmake-build-system.scm (configure): Set CMAKE_LIBRARY_PATH to LIBRARY_PATH and CMAKE_INCLUDE_PATH to CPATH.
* guix/build/cmake-build-system.scm, guix/build-system/cmake.scm: New files. * Makefile.am (MODULES): Add them.