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.

sys/bsp/bsp.seed

@@ -0,0 +1,38 @@
+[seed]
+name = 'bsp'
+
+[build]
+build_system = 'generic'
+build_command = {
+	args = [
+		'root-src:toolchain/mkbsp/mkbsp',
+		'--preset',
+		'src:rosetta.preset',
+		'--sysroot',
+		'install:.',
+		'--out',
+		'bin:rosetta-system.bsp',
+	],
+}
+watch_files = [ 'install:**' ]
+
+[dependency]
+seeds = [
+	'ld',
+	'bshell',
+	'libc',
+	'libpthread',
+	'libfx',
+	'liblaunch',
+	'libfs',
+	'libxpc',
+	'herdd',
+	'herdd-targets',
+	'nsd',
+	'devmd',
+]
+
+[install]
+"/boot" = [ 'bin:rosetta-system.bsp' ]
+
+# vim: ft=toml