Vendor dependencies for 0.3.0 release

vendor/metal/examples/compute/compute-argument-buffer.metal

@@ -0,0 +1,14 @@
+#include <metal_stdlib>
+
+using namespace metal;
+
+struct SumInput {
+    device uint *data;
+    volatile device atomic_uint *sum;
+};
+
+kernel void sum(device SumInput& input [[ buffer(0) ]],
+                uint gid [[ thread_position_in_grid ]])
+{
+    atomic_fetch_add_explicit(input.sum, input.data[gid], memory_order_relaxed);
+}