bug 14537: vkGetPhysicalDeviceImageFormatProperties doesn't express all limitations (WIP)

Use VkSampleCountFlagBits exclusively.  Note that it can be casted to integer.

https://cvs.khronos.org/bugzilla/show_bug.cgi?id=14537
diff --git a/tests/image_tests.cpp b/tests/image_tests.cpp
index e24d60e..f8f2175 100644
--- a/tests/image_tests.cpp
+++ b/tests/image_tests.cpp
@@ -161,7 +161,7 @@
     //        VkExtent3D                            extent;
     //        uint32_t                                mipLevels;
     //        uint32_t                                arraySize;
-    //        uint32_t                                samples;
+    //        VkSampleCountFlagBits                   samples;
     //        VkImageTiling                        tiling;
     //        VkFlags                               usage;                      // VkImageUsageFlags
     //        VkFlags                               flags;                      // VkImageCreateFlags
@@ -177,7 +177,7 @@
     imageCreateInfo.extent.height = h;
     imageCreateInfo.extent.depth = 1;
     imageCreateInfo.mipLevels = mipCount;
-    imageCreateInfo.samples = 1;
+    imageCreateInfo.samples = VK_SAMPLE_COUNT_1_BIT;
     if ((image_fmt.linearTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT) &&
         (image_fmt.linearTilingFeatures & VK_FORMAT_FEATURE_COLOR_ATTACHMENT_BIT))
     {