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.

lib/libc/include/CMakeLists.txt

@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.31)
+project(libc-headers C)
+
+file(GLOB headers *.h)
+file(GLOB sys_headers sys/*.h)
+
+install(FILES ${headers} DESTINATION include)
+install(FILES ${sys_headers} DESTINATION include/sys)

lib/libc/include/libc-headers.seed

@@ -0,0 +1,16 @@
+[seed]
+name = 'libc-headers'
+
+[dependency]
+no_standard_dependencies = true
+
+[build]
+build_system = 'source-only'
+build_for = 'target'
+watch_files = [ 'src:**' ]
+
+[install]
+"/usr/include" = [ 'src:*.h' ]
+"/usr/include/sys" = [ 'src:sys/*.h' ]
+
+# vim: ft=toml