meta: replace cmake mono-build system with a custom build co-ordinator

every system component now has its own self-contained build system, and a
seed file describing the component and its build system and dependencies.

a new tool, meadow, collects and uses these seed files to build the
components into a full system. meadow also manages the target system root
and a host prefix where toolchain tools are installed to.

the build system has also been updated to use a new $ARCH-rosetta-gcc
compiler, and the patches files necessary to build it have been
added to toolchain/cross-compiler.

cmake/Msg-Interface.cmake

@@ -37,6 +37,7 @@ function(add_interface)
 		INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_CURRENT_BINARY_DIR})
 	add_dependencies(iflib-${arg_NAME} ifgen-${arg_NAME})
 	add_library(interface::${arg_NAME} ALIAS iflib-${arg_NAME})
+	install(FILES ${header_path} DESTINATION include/${arg_PARENT_DIR})
 endfunction(add_interface)
 
 function(iface_get_header_path)