OvmfPkg/EmuVariableFvbRuntimeDxe: always format an auth varstore header

OvmfPkg/EmuVariableFvbRuntimeDxe: always format an auth varstore header

In this patch, we extend commit d92eaabefbe0 ("OvmfPkg: simplify
VARIABLE_STORE_HEADER generation", 2016-02-05) to
EmuVariableFvbRuntimeDxe.

This is the difference between FvAndVarTemplate and
FvAndAuthenticatedVarTemplate:

> --- non-auth    2017-05-05 22:32:06.001512283 +0200
> +++ auth        2017-05-05 22:32:18.841364882 +0200
> @@ -1,7 +1,7 @@
>    //
> -  // Templates for standard (non-authenticated) variable FV header
> +  // Templates for authenticated variable FV header
>    //
> -  STATIC FVB_FV_HDR_AND_VARS_TEMPLATE FvAndVarTemplate = {
> +  STATIC FVB_FV_HDR_AND_VARS_TEMPLATE FvAndAuthenticatedVarTemplate = {
>      { // EFI_FIRMWARE_VOLUME_HEADER FvHdr;
>        // UINT8                     ZeroVector[16];
>        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
> @@ -34,7 +34,7 @@
>        EFI_FVH_REVISION,
>
>        // EFI_FV_BLOCK_MAP_ENTRY    BlockMap[1];
> -      {
> +      {
>          {
>            2, // UINT32 NumBlocks;
>            EMU_FVB_BLOCK_SIZE  // UINT32 Length;
> @@ -44,8 +44,8 @@
>      // EFI_FV_BLOCK_MAP_ENTRY     EndBlockMap;
>      { 0, 0 }, // End of block map
>      { // VARIABLE_STORE_HEADER      VarHdr;
> -      // EFI_GUID  Signature;
> -      EFI_VARIABLE_GUID,
> +        // EFI_GUID  Signature;     // need authenticated variables for secure boot
> +        EFI_AUTHENTICATED_VARIABLE_GUID,
>
>        // UINT32  Size;
>        (

After this change, using "-bios", the variable driver logs:

- with the SB feature enabled:
> Variable driver will work with auth variable format!
> Variable driver will work with auth variable support!

- with the SB feature disabled:
> Variable driver will work with auth variable format!
> Variable driver will continue to work without auth variable support!

Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>