frontbuffer enhancements to ANDROID_vulkan_native_buffer

Since VK_KHR_swapchain is implemented entirely in libvulkan, we need an
image-level mechanism to inform the driver that a swapchain image will
be used for front-buffered rendering. This is implemented by chaining
another structure off of the VkImageCreateInfo passed to the driver when
creating swapchain images.

V2: Don't foul up api file. Rerun code generators.
V3: Rename VkNativeBuffer2ANDROID structure to
VkSwapchainImageCreateInfoANDROID
V4: Provide nulldrv stub for new function
V5: rebase.

Change-Id: I4447400cb1782440638e4c8816b081dd8923ddb9
Test: compile
diff --git a/vulkan/nulldrv/null_driver.cpp b/vulkan/nulldrv/null_driver.cpp
index 05ebcac..c403ede 100644
--- a/vulkan/nulldrv/null_driver.cpp
+++ b/vulkan/nulldrv/null_driver.cpp
@@ -886,6 +886,16 @@
     return VK_SUCCESS;
 }
 
+VkResult GetSwapchainGrallocUsage2ANDROID(VkDevice,
+                                          VkFormat,
+                                          VkImageUsageFlags,
+                                          VkSwapchainImageUsageFlagsANDROID,
+                                          int* grallocUsage) {
+    // The null driver never reads or writes the gralloc buffer
+    *grallocUsage = 0;
+    return VK_SUCCESS;
+}
+
 VkResult AcquireImageANDROID(VkDevice,
                              VkImage,
                              int fence,