automation: add alpine linux 3.12 x86 build container

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Wei Liu <wl@xen.org>

automation/build/alpine/3.12.dockerfile

@@ -0,0 +1,52 @@
+FROM alpine:3.12
+LABEL maintainer.name="The Xen Project" \
+      maintainer.email="xen-devel@lists.xenproject.org"
+
+ENV USER root
+
+RUN mkdir /build
+WORKDIR /build
+
+# build depends
+RUN \
+  # apk
+  apk update && \
+  \
+  # xen build deps
+  apk add argp-standalone && \
+  apk add autoconf && \
+  apk add automake && \
+  apk add bash && \
+  apk add curl && \
+  apk add curl-dev && \
+  apk add dev86 && \
+  apk add gcc  && \
+  apk add clang  && \
+  apk add gettext && \
+  apk add git && \
+  apk add iasl && \
+  apk add libaio-dev && \
+  apk add linux-headers && \
+  apk add make && \
+  apk add musl-dev  && \
+  apk add libc6-compat && \
+  apk add ncurses-dev && \
+  apk add patch  && \
+  apk add python3-dev && \
+  apk add texinfo && \
+  apk add util-linux-dev && \
+  apk add xz-dev && \
+  apk add yajl-dev && \
+  apk add zlib-dev && \
+  \
+  # qemu build deps
+  apk add bison && \
+  apk add flex && \
+  apk add glib-dev && \
+  apk add libattr && \
+  apk add libcap-ng-dev && \
+  apk add pixman-dev && \
+  \
+  # cleanup
+  rm -rf /tmp/* && \
+  rm -f /var/cache/apk/*