message: Fix incorrect VkDescriptorPoolSize in negativeviewportheight.
  There is assertion fail in negativeviewportheight (AMD GPU). The example create two VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER for descriptorSet, but descriptorCount is one in descriptorPool.
diff: @@ -204,7 +204,7 @@ public:
  VkPipelineLayoutCreateInfo pipelineLayoutCI = vks::initializers::pipelineLayoutCreateInfo(&descriptorSetLayout, 1);
  VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pipelineLayoutCI, nullptr, &pipelineLayout));
  - VkDescriptorPoolSize poolSize = vks::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1);
  + VkDescriptorPoolSize poolSize = vks::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 2);
  VkDescriptorPoolCreateInfo descriptorPoolCI = vks::initializers::descriptorPoolCreateInfo(1, &poolSize, 2);
  VK_CHECK_RESULT(vkCreateDescriptorPool(device, &descriptorPoolCI, nullptr, &descriptorPool));
  