docker: Dedup cargo and chef dockerfiles.

Signed-off-by: Jason Volk <jason@zemos.net>

docker/Dockerfile.source

@@ -28,23 +28,18 @@ ARG CARGO_TARGET
 ARG CARGO_TERM_VERBOSE=0
 ARG RUST_BACKTRACE
 ARG JEMALLOC_OVERRIDE
-#ARG ZSTD_SYS_USE_PKG_CONFIG=0
 ARG ROCKSDB_LIB_DIR
 
 WORKDIR /
 COPY --link --from=input . .
-
-WORKDIR /
 COPY --link --from=rust ${RUST_HOME} ${RUST_HOME}
+COPY --link --from=source /usr/src/tuwunel /usr/src/tuwunel
 
 WORKDIR /usr/src/tuwunel
-COPY --link --from=source /usr/src/tuwunel .
-
 ENV PATH="${CARGO_HOME}/bin:$PATH"
 ENV CARGO_TERM_VERBOSE="${CARGO_TERM_VERBOSE}"
 ENV RUST_BACKTRACE="${RUST_BACKTRACE}"
 ENV JEMALLOC_OVERRIDE="${JEMALLOC_OVERRIDE}"
-#ENV ZSTD_SYS_USE_PKG_CONFIG="${ZSTD_SYS_USE_PKG_CONFIG}"
 ENV ROCKSDB_LIB_DIR="${ROCKSDB_LIB_DIR}"
 RUN \
 --mount=type=cache,dst=${RUSTUP_HOME}/downloads,sharing=locked \