OvmfPkg: QemuFlashFvbServicesRuntimeDxe: adhere to -D SMM_REQUIRE

When the user requires "security" by passing -D SMM_REQUIRE, and
consequently by setting PcdSmmSmramRequire, enforce flash-based variables.

Furthermore, add two ASSERT()s to catch if the wrong module were pulled
into the build.

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

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19063 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c

@@ -17,6 +17,7 @@
 #include <Guid/EventGroup.h>
 #include <Library/DebugLib.h>
 #include <Library/DevicePathLib.h>
+#include <Library/PcdLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiRuntimeLib.h>
 #include <Protocol/DevicePath.h>
@@ -34,6 +35,8 @@ InstallProtocolInterfaces (
   EFI_HANDLE                         FwbHandle;
   EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL *OldFwbInterface;
 
+  ASSERT (!FeaturePcdGet (PcdSmmSmramRequire));
+
   //
   // Find a handle with a matching device path that has supports FW Block
   // protocol