patches/bmake{,_host}.local.patch: fix parallel build.
    groups/010.host_deps.group:bmake_host:${PKG_MAKEFLAGS_LOADAVG}: set to none.
    groups/010.host_deps.group:bmake_host:${PKG_MAKEFLAGS_PARALLELISE}: revert to default.
    groups/231.native_packages_etc.group:bmake:${PKG_MAKEFLAGS_LOADAVG}: set to none.
    groups/231.native_packages_etc.group:bmake:${PKG_MAKEFLAGS_PARALLELISE}: revert to default.