Dockerfile: use clang to build dockerd/docker-proxy

Static binaries for dockerd are broken on armhf and armel (32-bit).
It seems to be an issue with GCC as building using clang solves
this issue. Also adds extra instruction to prefer ld for
cross-compiling arm64 in bullseye otherwise it doesn't link.

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

Dockerfile

@@ -547,6 +547,12 @@ WORKDIR /go/src/github.com/docker/docker
 ENV GO111MODULE=off
 ENV CGO_ENABLED=1
 ARG DEBIAN_FRONTEND
+RUN --mount=type=cache,sharing=locked,id=moby-build-aptlib,target=/var/lib/apt \
+    --mount=type=cache,sharing=locked,id=moby-build-aptcache,target=/var/cache/apt \
+        apt-get update && apt-get install --no-install-recommends -y \
+            clang \
+            lld \
+            llvm
 ARG TARGETPLATFORM
 RUN --mount=type=cache,sharing=locked,id=moby-build-aptlib,target=/var/lib/apt \
     --mount=type=cache,sharing=locked,id=moby-build-aptcache,target=/var/cache/apt \
@@ -573,6 +579,12 @@ ARG PACKAGER_NAME
 # PREFIX overrides DEST dir in make.sh script otherwise it fails because of
 # read only mount in current work dir
 ENV PREFIX=/tmp
+RUN <<EOT
+  # in bullseye arm64 target does not link with lld so configure it to use ld instead
+  if xx-info is-cross && [ "$(xx-info arch)" = "arm64" ]; then
+    XX_CC_PREFER_LINKER=ld xx-clang --setup-target-triple
+  fi
+EOT
 RUN --mount=type=bind,target=. \
     --mount=type=tmpfs,target=cli/winresources/dockerd \
     --mount=type=tmpfs,target=cli/winresources/docker-proxy \