virtualisation.qemu.program: Remove

This option is defined in qemu-vm.nix, but that module is not always
imported.

http://hydra.nixos.org/build/44817443
(cherry picked from commit 03c55005dfd6fbcd5cf8e00128a3bb6336b3bc0f)

nixos/lib/testing.nix

···
         cp ${./test-driver/Logger.pm} $libDir/Logger.pm
 
         wrapProgram $out/bin/nixos-test-driver \
-          --prefix PATH : "${lib.makeBinPath [ qemu_kvm vde2 netpbm coreutils ]}" \
+          --prefix PATH : "${lib.makeBinPath [ qemu_test vde2 netpbm coreutils ]}" \
           --prefix PERL5LIB : "${with perlPackages; lib.makePerlPath [ TermReadLineGnu XMLWriter IOTty FileSlurp ]}:$out/lib/perl5/site_perl"
       '';
   };

nixos/modules/testing/test-instrumentation.nix

···
 
     networking.usePredictableInterfaceNames = false;
 
-    # Make sure we use a patched QEMU that ignores file ownership.
-    virtualisation.qemu.program = "${pkgs.qemu_test}/bin/qemu-kvm";
-
     # Make it easy to log in as root when running the test interactively.
     users.extraUsers.root.initialHashedPassword = mkOverride 150 "";
 

nixos/modules/virtualisation/qemu-vm.nix

···
       '')}
 
       # Start QEMU.
-      exec ${cfg.qemu.program} \
+      exec ${pkgs.qemu_test}/bin/qemu-kvm \
           -name ${vmName} \
           -m ${toString config.virtualisation.memorySize} \
           ${optionalString (pkgs.stdenv.system == "x86_64-linux") "-cpu kvm64"} \
···
       };
 
     virtualisation.qemu = {
-      program = mkOption {
-        type = types.path;
-        default = "${pkgs.qemu_kvm}/bin/qemu-kvm";
-        defaultText = "\${pkgs.qemu_kvm}/bin/qemu-kvm";
-        example = literalExample "\${pkgs.qemu_test}/bin/qemu-kvm";
-        description = "The QEMU variant used to start the VM.";
-      };
-
       options =
         mkOption {
           type = types.listOf types.unspecified;