Add Norcroft C/C++ (ncc-ng) compiler build (#121)

Add build support for the Norcroft C/C++ compiler from
https://github.com/Norcroft/ncc-ng

Builds ncc (ARM C) and n++ (ARM C++) compilers. Thumb compilers
(ntcc, nt++) are disabled pending an upstream fix for missing
TOOLVER_TCC definition.

Related: compiler-explorer/compiler-explorer#8297

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: mattgodbolt

.github/workflows/build.yml

@@ -17,6 +17,7 @@ jobs:
         - lc3
         - misc
         - nasm
+        - ncc-ng
         - python
         - pythran
         - rocm

Dockerfile.ncc-ng

@@ -0,0 +1,14 @@
+FROM ubuntu:22.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+RUN apt update -y -q && apt upgrade -y -q && \
+    apt install -y -q \
+    build-essential \
+    git \
+    xz-utils
+
+RUN mkdir -p /root
+COPY ncc-ng /root/
+COPY common.sh /root/
+
+WORKDIR /root

ncc-ng/build.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+
+set -ex
+source common.sh
+
+VERSION=$1
+if [[ "${VERSION}" = "trunk" ]]; then
+    VERSION=trunk-$(date +%Y%m%d)
+    BRANCH=main
+else
+    BRANCH=${VERSION}
+fi
+
+URL=https://github.com/Norcroft/ncc-ng
+
+FULLNAME=ncc-ng-${VERSION}
+OUTPUT=$2/${FULLNAME}.tar.xz
+
+REVISION="ncc-ng-$(get_remote_revision "${URL}" "heads/${BRANCH}")"
+LAST_REVISION="${3:-}"
+
+initialise "${REVISION}" "${OUTPUT}" "${LAST_REVISION}"
+
+PREFIX=$(pwd)/prefix
+DIR=$(pwd)/ncc-ng
+
+git clone --depth 1 -b "${BRANCH}" "${URL}" "${DIR}"
+
+cd "${DIR}"
+make all      # builds ncc and n++ (ARM backend)
+# TODO: Thumb compilers (ntcc, nt++) fail to build due to missing TOOLVER_TCC in toolver.h
+# Uncomment when upstream fixes: make ntcc nt++
+
+mkdir -p "${PREFIX}/bin"
+cp bin/* "${PREFIX}/bin/"
+
+complete "${PREFIX}" "${FULLNAME}" "${OUTPUT}"