fix multiple copy sync hazard

src/Refresh_Driver_Vulkan.c

@@ -7882,6 +7882,14 @@ static void VULKAN_SetBufferData(
 		vulkanBuffer
 	);
 
+	// this janky call will wait for transfer writes to finish!
+	VULKAN_INTERNAL_BufferMemoryBarrier(
+		renderer,
+		vulkanCommandBuffer->commandBuffer,
+		RESOURCE_ACCESS_TRANSFER_WRITE,
+		vulkanBuffer
+	);
+
 	bufferCopy.srcOffset = transferBuffer->offset;
 	bufferCopy.dstOffset = offsetInBytes;
 	bufferCopy.size = (VkDeviceSize) dataLength;