Add script for end-to-end Ibex toolchain build

Author: jwnrt

contrib/build-opentitan-dist.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env sh
+
+set -ex
+
+./build-binutils.sh "riscv32-unknown-elf"
+
+./build-clang-with-args.sh \
+  "lowrisc-toolchain-rv32imcb" \
+  "Release" \
+  "riscv32-unknown-elf" \
+  "rv32imc_zba_zbb_zbc_zbs" \
+  "ilp32" \
+  "medany"
+
+./create-prefixed-archive.sh \
+  "lowrisc-toolchain-rv32imcb" \
+  "build/"