gtk4: fix build w/ newer vulkan

srcpkgs/gtk4/patches/vulkan-VK_RESULT_RANGE_SIZE.patch

@@ -0,0 +1,12 @@
+--- gdk/gdkvulkancontext.c	2018-06-26 13:48:16.000000000 +0200
++++ gdk/gdkvulkancontext.c	2020-07-26 16:28:33.487718532 +0200
+@@ -190,7 +190,9 @@
+     case VK_ERROR_FRAGMENTATION_EXT:
+       return "A descriptor pool creation has failed due to fragmentation";
+ #endif
++#if defined(VK_RESULT_RANGE_SIZE)
+     case VK_RESULT_RANGE_SIZE:
++#endif
+     case VK_RESULT_MAX_ENUM:
+     default:
+       return "Unknown Vulkan error.";