manibuilder: Prepare a `source' container from local repository

Clone the local repository into a `mani/source' container. This can be
copied during the build of our test containers,  to avoid cloning over
network.

Change-Id: I28fea93f9f77aa4d41143046081f4c6fd743c12e
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.sourcearcade.org/c/flashprog/+/361
diff --git a/util/manibuilder/Dockerfile.source b/util/manibuilder/Dockerfile.source
new file mode 100644
index 0000000..d8bf029
--- /dev/null
+++ b/util/manibuilder/Dockerfile.source
@@ -0,0 +1,4 @@
+FROM scratch
+
+ARG SRC_TMP=
+COPY ${SRC_TMP} /source