Fix for potentially uninitialized variables
Fix for potentially uninitialized variables

This change adds a constructor for a struct which sets the members that
do not have a constructor of their own to known values.

This potentially affects anything that uses the reference rasterizer,
but should not change any test results.

Affects:
*

Components: Framework
VK-GL-CTS issue: 3434

Change-Id: Ie874b4baa4d2ff5a8aa66f9ea2c3cd11b37edb64

KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/VK-GL-CTS