Add OvmfRng include snippets with the random number generator
configuration for OVMF. Include RngDxe, build with BaseRngLib,
so the rdrand instruction is used (if available).
Also move VirtioRng to the include snippets.
Use the new include snippets for OVMF builds.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Gerd Hoffmann