Automatically enable basic emulation on buildlers

Since my remote build machines are going to be limited to only my most
powerful systems, it makes sense that they are going to be able to use a
few cycles to do some basic emulation. So my x86_64-linux systems can
emulate aarch64 and i686 pretty easily to speed up the few things that I
would build on them

modules/nixos/remote-builder.nix

@@ -19,6 +19,13 @@ with lib;
       isNormalUser = true;
       useDefaultShell = true;
     };
+    # The builder user needs to be trusted to submit builds
     nix.settings.trusted-users = [ config.users.users.remote-builder-user.name ];
+    # If the system is powerful enough to be a remote builder, it should
+    # be powerful enough to do some basic qemu stuff
+    boot.binfmt.emulatedSystems = [
+      "i686-linux"
+      "aarch64-linux"
+    ];
   };
 }