Build against google-grpc 1.11, where md.Get() does not exist.
This patch is based on the commit that introduced md.Get() in google-grpc:
<https://github.com/grpc/grpc-go/commit/
291de7f0>.
Please drop this patch as soon as we build docker against google-grpc >= 1.12.
Origin: vendor, Debian
Forwarded: not-needed, Debian-specific
Signed-off-by: Arnaud Rebillout <arnaud.rebillout@collabora.com>
Gbp-Pq: Name buildkit-build-against-google-grpc-1.11.patch