[vulkan] Define VK_USE_PLATFORM_FUCHSIA

VK_USE_PLATFORM_MAGMA_KHR is old and will be removed.

vulkan/vulkan_interface.h

@@ -22,6 +22,9 @@
 #ifndef VK_USE_PLATFORM_MAGMA_KHR
 #define VK_USE_PLATFORM_MAGMA_KHR 1
 #endif  // VK_USE_PLATFORM_MAGMA_KHR
+#ifndef VK_USE_PLATFORM_FUCHSIA
+#define VK_USE_PLATFORM_FUCHSIA 1
+#endif  // VK_USE_PLATFORM_FUCHSIA
 #endif  // OS_FUCHSIA
 
 #if !VULKAN_LINK_STATICALLY