Build docker with gccgo, requires host to contain gccgo 5.0

Addresses #9207
Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>

hack/make/.dockerinit-gccgo

@@ -0,0 +1,29 @@
+#!/bin/bash
+set -e
+
+IAMSTATIC="true"
+source "$(dirname "$BASH_SOURCE")/.go-autogen"
+
+go build --compiler=gccgo \
+	-o "$DEST/dockerinit-$VERSION" \
+	"${BUILDFLAGS[@]}" \
+	--gccgoflags "
+		-g
+		-Wl,--no-export-dynamic
+		$EXTLDFLAGS_STATIC_DOCKER
+	" \
+	./dockerinit
+
+echo "Created binary: $DEST/dockerinit-$VERSION"
+ln -sf "dockerinit-$VERSION" "$DEST/dockerinit"
+
+sha1sum=
+if command -v sha1sum &> /dev/null; then
+	sha1sum=sha1sum
+else
+	echo >&2 'error: cannot find sha1sum command or equivalent'
+	exit 1
+fi
+
+# sha1 our new dockerinit to ensure separate docker and dockerinit always run in a perfect pair compiled for one another
+export DOCKER_INITSHA1="$($sha1sum $DEST/dockerinit-$VERSION | cut -d' ' -f1)"