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.

toolchain/mkbsp/main.py

@@ -0,0 +1,46 @@
+import sys
+import os
+import tomli
+from colorama import init as colorama_init
+from colorama import Fore, Style
+from args import Args
+from preset import Preset
+from bsp import BSP
+
+
+def main():
+    colorama_init()
+
+    args = Args(sys.argv)
+
+    preset_path = args.get_named('preset', 0, 1)
+    if preset_path is None:
+        print(f'{Fore.RED}Err:{Style.RESET_ALL} no preset specified')
+        return -1
+
+    out_path = args.get_named('out', 0, 1)
+    if out_path is None:
+        print(f'{Fore.RED}Err:{Style.RESET_ALL} no output path specified')
+        return -1
+
+    sysroot_path = args.get_named('sysroot', 0, 1)
+    if sysroot_path is None:
+        sysroot_path = '/'
+
+    preset = Preset(preset_path)
+
+    bsp = BSP(out_path, sysroot=sysroot_path)
+    for dst, src in preset.contents().items():
+        for src_filepath in src:
+            src_filename = os.path.basename(src_filepath)
+            dst_filepath = os.path.join(dst, src_filename)
+            bsp.add_file(src_filepath, dst_filepath)
+
+    bsp.set_bootstrap_program(preset.bootstrap_program())
+    bsp.close()
+
+    return 0
+
+
+if __name__ == '__main__':
+    exit(main())