bug 15022: Need a way to specify dummy descriptors for unused bindings (WIP)

Add binding to VkDescriptorSetLayoutBinding.

https://cvs.khronos.org/bugzilla/show_bug.cgi?id=15022
diff --git a/include/vulkan.h b/include/vulkan.h
index f233790..df7c461 100644
--- a/include/vulkan.h
+++ b/include/vulkan.h
@@ -1831,6 +1831,7 @@
 } VkSamplerCreateInfo;
 
 typedef struct VkDescriptorSetLayoutBinding {
+    uint32_t                                    binding;
     VkDescriptorType                            descriptorType;
     uint32_t                                    arraySize;
     VkShaderStageFlags                          stageFlags;