Refactor build scripts.

substrate/common.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+ROOT=`dirname "$0"`
+
+# A list of directories which contain wasm projects.
+SRCS=(
+	"polkadot/runtime/wasm"
+	"substrate/executor/wasm"
+	"demo/runtime/wasm"
+	"substrate/test-runtime/wasm"
+	"polkadot/parachain/test-chains/basic_add"
+)
+
+# Make pushd/popd silent.
+
+pushd () {
+	command pushd "$@" > /dev/null
+}
+
+popd () {
+	command popd "$@" > /dev/null
+}