Remove unused pWaitDstStageMask from Vulkan submit

pWaitDstStageMask is only meaningful when wait semaphores are used,
which this submit path does not use. This wasn't causing errors in
practice because vkWaitForFences is called after every submit,
preventing concurrent in-flight command buffers. The compute dispatch
submit passed VK_PIPELINE_STAGE_TRANSFER_BIT, intending to wait for
the prior buffer transfer submit to complete, but pWaitDstStageMask is
a destination stage mask — it specifies which stages in the current
submit to block until a wait semaphore signals, not which prior stages
to wait on. Without semaphores this had no effect.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: MarijnS95

lib/API/VK/Device.cpp

@@ -1106,8 +1106,7 @@ class VulkanDevice : public offloadtest::Device {
     return llvm::Error::success();
   }
 
-  llvm::Error executeCommandBuffer(InvocationState &IS,
-                                   VkPipelineStageFlags WaitMask = 0) {
+  llvm::Error executeCommandBuffer(InvocationState &IS) {
     if (vkEndCommandBuffer(IS.CmdBuffer))
       return llvm::createStringError(std::errc::device_or_resource_busy,
                                      "Could not end command buffer.");
@@ -1116,7 +1115,6 @@ class VulkanDevice : public offloadtest::Device {
     SubmitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
     SubmitInfo.commandBufferCount = 1;
     SubmitInfo.pCommandBuffers = &IS.CmdBuffer;
-    SubmitInfo.pWaitDstStageMask = &WaitMask;
     VkFenceCreateInfo FenceInfo = {};
     FenceInfo.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
     VkFence Fence;
@@ -2305,7 +2303,7 @@ class VulkanDevice : public offloadtest::Device {
     if (auto Err = createCommands(P, State))
       return Err;
     llvm::outs() << "Commands created.\n";
-    if (auto Err = executeCommandBuffer(State, VK_PIPELINE_STAGE_TRANSFER_BIT))
+    if (auto Err = executeCommandBuffer(State))
       return Err;
     llvm::outs() << "Executed compute command buffer.\n";
     if (auto Err = readBackData(P, State))