Preserve hii section in GCC binaries

According to UEFI spec:
Once an image is loaded, LoadImage() installs
EFI_HII_PACKAGE_LIST_PROTOCOL on the handle if the image contains a
custom PE/COFF resource with the type 'HII'. The protocol's
interface pointer points to the HII package list which is contained
in the resource's data.

This is controlled by the UEFI_HII_RESOURCE_SECTION define in the INF
file.  When present the HII resource is linked with the module
binary.

Unfortunately GCC-built binaries have been stripping the .hii section
entirely.  See  "[edk2] HII gEfiHiiPackageListProtocolGuid problem
with  GCC48(VS2012x86 works)"
http://thread.gmane.org/gmane.comp.bios.tianocore.devel/13438
http://thread.gmane.org/gmane.comp.bios.tianocore.devel/14899

This patch tells the linker to preserve the .hii sections

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Thomas Palmer <thomas.palmer@hpe.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Bruce Cran <bruce.cran@gmail.com>
Reviewed-by: Bruce Cran <bruce.cran@gmail.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Scripts/GccBase.lds

@@ -4,6 +4,7 @@
 
   Copyright (c) 2010 - 2015, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
+  (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>
 
   This program and the accompanying materials are licensed and made available under
   the terms and conditions of the BSD License that accompanies this distribution.
@@ -57,6 +58,10 @@ SECTIONS {
     *(.rela .rela.*)
   }
 
+  .hii : ALIGN(CONSTANT(COMMONPAGESIZE)) {
+    KEEP (*(.hii))
+  }
+
   /DISCARD/ : {
     *(.note.GNU-stack)
     *(.gnu_debuglink)