NetworkPkg:Enable Http Boot over Ipv6 stack

Add new features to support Http boot over ipv6 stack.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18743 6f19259b-4bc3-4df7-8a09-765794883524

NetworkPkg/HttpBootDxe/HttpBootDhcp4.h

@@ -245,6 +245,17 @@ typedef struct {
   EFI_DHCP4_PACKET_OPTION     *OptList[HTTP_BOOT_DHCP4_TAG_INDEX_MAX];
 } HTTP_BOOT_DHCP4_PACKET_CACHE;
 
+/**
+  Select an DHCPv4 or DHCP6 offer, and record SelectIndex and SelectProxyType.
+
+  @param[in]  Private             Pointer to HTTP boot driver private data.
+
+**/
+VOID
+HttpBootSelectDhcpOffer (
+  IN HTTP_BOOT_PRIVATE_DATA  *Private
+  );
+
 /**
   Start the D.O.R.A DHCPv4 process to acquire the IPv4 address and other Http boot information.