Squash all build steps in the dockerfile, producing a much smaller image

Keep the old dockerfile with a different file name, for easier
testing/debugging (where later steps can be tweaked without
rebuilding everything).

Dockerfile.dev

@@ -0,0 +1,74 @@
+FROM ubuntu:16.04
+
+RUN apt-get update -qq && apt-get install -qqy \
+    git wget bzip2 file unzip libtool pkg-config cmake build-essential \
+    automake yasm gettext autopoint vim python git-svn ninja-build && \
+    apt-get clean -y && \
+    rm -rf /var/lib/apt/lists/*
+
+
+RUN git config --global user.name "LLVM MinGW" && \
+    git config --global user.email root@localhost
+
+WORKDIR /build
+
+ARG CORES=4
+
+ENV TOOLCHAIN_PREFIX=/opt/llvm-mingw
+
+# Build LLVM
+COPY build-llvm.sh .
+RUN ./build-llvm.sh $TOOLCHAIN_PREFIX
+
+ENV TOOLCHAIN_ARCHS="i686 x86_64 armv7 aarch64"
+
+# Install the usual $TUPLE-clang binaries
+COPY wrappers/*.sh ./wrappers/
+COPY install-wrappers.sh .
+RUN ./install-wrappers.sh $TOOLCHAIN_PREFIX
+
+# Cheating: Pull windres from the normal binutils package.
+# llvm-rc isn't fully usable as a replacement for windres yet.
+RUN apt-get update -qq && \
+    apt-get install -qqy binutils-mingw-w64-x86-64 && \
+    cp /usr/bin/x86_64-w64-mingw32-windres $TOOLCHAIN_PREFIX/bin/x86_64-w64-mingw32-windresreal && \
+    apt-get remove -qqy binutils-mingw-w64-x86-64 && \
+    apt-get clean -y && \
+    rm -rf /var/lib/apt/lists/*
+
+# Build MinGW-w64
+COPY build-mingw-w64.sh .
+RUN ./build-mingw-w64.sh $TOOLCHAIN_PREFIX
+
+# Build compiler-rt
+COPY build-compiler-rt.sh .
+RUN ./build-compiler-rt.sh $TOOLCHAIN_PREFIX
+
+# Build C test applications
+ENV PATH=$TOOLCHAIN_PREFIX/bin:$PATH
+
+COPY test/*.c ./test/
+RUN cd test && \
+    for arch in $TOOLCHAIN_ARCHS; do \
+        for test in hello hello-tls crt-test; do \
+            $arch-w64-mingw32-clang $test.c -o $test-$arch.exe || exit 1; \
+        done; \
+    done
+
+# Build libunwind/libcxxabi/libcxx
+COPY build-libcxx.sh merge-archives.sh ./
+RUN ./build-libcxx.sh $TOOLCHAIN_PREFIX
+
+# Build C++ test applications
+COPY test/*.cpp ./test/
+RUN cd test && \
+    for arch in $TOOLCHAIN_ARCHS; do \
+        for test in hello-cpp hello-exception; do \
+            $arch-w64-mingw32-clang++ $test.cpp -o $test-$arch.exe || exit 1; \
+        done; \
+    done
+
+# Strip the final toolchain. (This doesn't reduce the total docker image
+# size as long as it is in a separate RUN layer though.)
+COPY strip-llvm.sh .
+RUN ./strip-llvm.sh $TOOLCHAIN_PREFIX