Add podman static build

We’re now able to build a static podman binary based on a custom nix
derivation. This is integrated in cirrus as well, whereas a later target
would be to provide a self-contained static binary bundle which can be
installed on any Linux x64-bit system.

Fixes: https://github.com/containers/libpod/issues/1399

Signed-off-by: Sascha Grunert <sgrunert@suse.com>

.gitignore

@@ -31,3 +31,4 @@ release.txt
 /test/copyimg/copyimg
 /test/goecho/goecho
 .vscode*
+result-bin