gpu: add Surface.DescriptorFromXlibWindow

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

gpu/TODO-webgpu.h

@@ -1,9 +1,3 @@
-pub const WGPUSurfaceDescriptorFromXlibWindow = extern struct {
-    chain: ChainedStruct,
-    display: *anyopaque,
-    window: u32,
-};
-
 pub const WGPUSwapChainDescriptor = extern struct {
     next_in_chain: *const ChainedStruct,
     label: ?[*:0]const u8 = null,

gpu/src/surface.zig

@@ -47,4 +47,10 @@ pub const Surface = enum(usize) {
         chain: ChainedStruct,
         swap_chain_panel: *anyopaque,
     };
+
+    pub const DescriptorFromXlibWindow = extern struct {
+        chain: ChainedStruct,
+        display: *anyopaque,
+        window: u32,
+    };
 };