Split the build stage to smaller steps.

Easier to iterate when debugging with better caching.

Dockerfile

@@ -15,14 +15,11 @@ RUN apk add --update --no-cache \
     ;
 ARG Version
 ENV VERSION="$Version"
-# hadolint ignore=DL3020
-ADD "https://github.com/varnish/hitch/archive/${VERSION}.tar.gz" /
+RUN wget "https://github.com/varnish/hitch/archive/${VERSION}.tar.gz" && \
+    tar --no-same-owner --no-same-permissions -xzf "${VERSION}.tar.gz"
 ENV LDFLAGS="--static"
-# hadolint ignore=DL3003
-RUN tar -xzf "${VERSION}.tar.gz" && \
-    cd "hitch-${VERSION}" && \
-    ./bootstrap && \
-    ./configure && \
+WORKDIR /hitch-$Version
+RUN ./bootstrap && \
     make && \
     make install