Refactor build scripts.

parachain/test-chains/basic_add/build.sh

+#!/bin/bash
+set -e
+
+# Make LLD produce a binary that imports memory from the outside environment.
+export RUSTFLAGS="-C link-arg=--import-memory"
+
+cargo +nightly build --target=wasm32-unknown-unknown --release --no-default-features
+
+for i in basic_add
+do
+	wasm-gc target/wasm32-unknown-unknown/release/$i.wasm target/wasm32-unknown-unknown/release/$i.compact.wasm
+done

parachain/test-chains/build.sh

-#!/bin/sh
+#!/bin/bash
 set -e
 
 rm -rf ./target

runtime/wasm/build.sh

-#!/bin/sh
+#!/bin/bash
 set -e
 
 cargo +nightly build --target=wasm32-unknown-unknown --release

runtime/wasm/init.sh

-#!/bin/sh
-
-rustup update nightly
-rustup target add wasm32-unknown-unknown --toolchain nightly
-rustup update stable
-cargo +nightly install --git https://github.com/alexcrichton/wasm-gc
-cargo +nightly install --git https://github.com/pepyakin/wasm-export-table.git