Introduce an include file with dynamic PCDs to simplify the usage of
the network stage. This allows us to stop manually adding
`PcdIPv4PXESupport` and `PcdIPv6PXESupport` to the DSC file.
`NETWORK_IP4_ENABLE` and `NETWORK_IP6_ENABLE` are not used because
PXEv4 and PXEv6 boot support can be controlled from the QEMU command
line.
Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>
Signed-off-by: Aleksandr Goncharov <chat@joursoir.net>
1db5895c39