build: use jinx in the build system

now uses jinx to build a cross toolchain, mlibc, bash and the kernel. also made scheduler temporarily run /usr/bin/bash instead of /sbin/init

source-recipes/mlibc

@@ -0,0 +1,12 @@
+name=mlibc
+version=2.3.0
+source_method=tarball
+tarball_url="https://github.com/managarm/mlibc/archive/refs/tags/${version}.tar.gz"
+tarball_sha512=3d5c866d43d1a5094954747f18b9cb3cbdbf7136ebc8b61de0d203fcf905220cdf59911c20ecd7bc085e57dcff721ca32f35990f9042ca7835bdaa98443f96d5
+hostdeps=""
+
+regenerate() {
+	mkdir -p ${source_dir}/sysdeps/astral/include/
+	ln -sv ../../../abis/linux/x86_64/ ${source_dir}/sysdeps/astral/include/abi-bits
+        true
+}