vulkan: Update vulkan headers to 1.0.38

Catches up with the current upstream header. Preserves the local changes
for incremental present.

V2: Fix indentation issues
V3: Add missing struct and defines for EXT_validation_flags

Change-Id: I6e4f44e0eba8de00b010a6918ec2ba92614cc6bc
Test: Ensured cube demo still works
diff --git a/vulkan/libvulkan/api_gen.cpp b/vulkan/libvulkan/api_gen.cpp
index 4004135..d70135b 100644
--- a/vulkan/libvulkan/api_gen.cpp
+++ b/vulkan/libvulkan/api_gen.cpp
@@ -17,9 +17,7 @@
 // WARNING: This file is generated. See ../README.md for instructions.
 
 #include <string.h>
-
 #include <algorithm>
-
 #include <android/log.h>
 
 // to catch mismatches between vulkan.h and this file
@@ -453,8 +451,10 @@
         "vkEnumerateInstanceLayerProperties",
         "vkEnumeratePhysicalDevices",
         "vkGetInstanceProcAddr",
+        "vkGetPhysicalDeviceExternalImageFormatPropertiesNV",
         "vkGetPhysicalDeviceFeatures",
         "vkGetPhysicalDeviceFormatProperties",
+        "vkGetPhysicalDeviceGeneratedCommandsPropertiesNVX",
         "vkGetPhysicalDeviceImageFormatProperties",
         "vkGetPhysicalDeviceMemoryProperties",
         "vkGetPhysicalDeviceProperties",