Upgradeable validation functions (#918)

* upgrade primitives to allow changing validation function

* set up storage schema for old parachains code

* fix compilation errors

* fix test compilation

* add some tests for past code meta

* most of the runtime logic for code upgrades

* implement old-code pruning

* add a couple tests

* clean up remaining TODOs

* add a whole bunch of tests for runtime functionality

* remove unused function

* fix runtime compilation

* extract some primitives to parachain crate

* add validation-code upgrades to validation params and result

* extend validation params with code upgrade fields

* provide maximums to validation params

* port test-parachains

* add a code-upgrader test-parachain and tests

* fix collator tests

* move test-parachains to own folder to work around compilation errors

* fix test compilation

* update the Cargo.lock

* fix parachains tests

* remove dbg! invocation

* use new pool in code-upgrader

* bump lockfile

* link TODO to issue

polkadot/parachain/test-parachains/halt/src/lib.rs

@@ -0,0 +1,49 @@
+// Copyright 2019-2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Basic parachain that executes forever.
+
+#![no_std]
+#![cfg_attr(not(feature = "std"), feature(core_intrinsics, lang_items, core_panic_info, alloc_error_handler))]
+
+// Make the WASM binary available.
+#[cfg(feature = "std")]
+include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs"));
+
+#[cfg(not(feature = "std"))]
+#[panic_handler]
+#[no_mangle]
+pub fn panic(_info: &core::panic::PanicInfo) -> ! {
+	unsafe {
+		core::intrinsics::abort()
+	}
+}
+
+#[cfg(not(feature = "std"))]
+#[alloc_error_handler]
+#[no_mangle]
+pub fn oom(_: core::alloc::Layout) -> ! {
+	unsafe {
+		core::intrinsics::abort();
+	}
+}
+
+#[cfg(not(feature = "std"))]
+#[no_mangle]
+pub extern fn validate_block(params: *const u8, len: usize) -> usize {
+	loop {}
+}
+