Enable shadow filtering tests for non-filterable formats

The spec says that you don't need to be able to filter the actual format
in order to filter the results of a shadow comparison. Enable this in
the texture tests.

Component: Vulkan
VK-GL-CTS issue: 2834
Affects: dEQP-VK.texture.shadow.*

Change-Id: I0879d8e77b84493d0be9677e9b4811a240c812b5
diff --git a/external/vulkancts/modules/vulkan/texture/vktTextureTestUtil.cpp b/external/vulkancts/modules/vulkan/texture/vktTextureTestUtil.cpp
index 14b2cbe..477f5a4 100644
--- a/external/vulkancts/modules/vulkan/texture/vktTextureTestUtil.cpp
+++ b/external/vulkancts/modules/vulkan/texture/vktTextureTestUtil.cpp
@@ -1251,7 +1251,8 @@
 			samplerCreateInfo.maxAnisotropy = maxAnisotropy;
 		}
 
-		if (samplerCreateInfo.magFilter == VK_FILTER_LINEAR || samplerCreateInfo.minFilter == VK_FILTER_LINEAR || samplerCreateInfo.mipmapMode == VK_SAMPLER_MIPMAP_MODE_LINEAR)
+		bool linFilt = (samplerCreateInfo.magFilter == VK_FILTER_LINEAR || samplerCreateInfo.minFilter == VK_FILTER_LINEAR || samplerCreateInfo.mipmapMode == VK_SAMPLER_MIPMAP_MODE_LINEAR);
+		if (linFilt && samplerCreateInfo.compareEnable == VK_FALSE)
 		{
 			const pipeline::TestTexture&	testTexture			= m_textureBindings[texUnit]->getTestTexture();
 			const VkFormat					textureFormat		= testTexture.isCompressed() ? mapCompressedTextureFormat(testTexture.getCompressedLevel(0, 0).getFormat())