headers: fix compilation error on android with vk_icd.h
headers: fix compilation error on android with vk_icd.h

Change allow us to refer to ANativeWindow from C code, fixes following
compilation error seen with clang 3.8.27580 (Android O prebuilts).

vk_icd.h:116:5: error: must use 'struct' tag to refer to type 'ANativeWindow'

Signed-off-by: Tapani Pälli <cdcb67a5e49297de94340ca09f25994bd5e7f762@intel.com>

KhronosGroup/Vulkan-Headers,KhronosGroup/Vulkan-Headers,KhronosGroup/Vulkan-Headers