Previously, `target_include_directories(mbgl-loop-uv PUBLIC ${NODEJS_INCLUDE_DIRS})` always applied. Compiles were working by accident because node is always installed in CI. Instead, split and inline loop-uv.cmake contents: linux uses `target_add_mason_package(mbgl-loop-uv PUBLIC libuv)`, node uses `target_include_directories(mbgl-loop-node PUBLIC ${NODEJS_INCLUDE_DIRS})`.