Have final present function perform a VkQueueWaitIdle()

This is just a small hack to prevent screen tearing.
Later, we should properly implement VkSemaphore to
prevent this.

Bug: b/132458423
Change-Id: I825f100a73c4b5b9b909eba83552cbec51ff1792
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31152
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Hernan Liatis <hliatis@google.com>

src/Vulkan/VkQueue.cpp

diff --git a/src/Vulkan/VkQueue.cpp b/src/Vulkan/VkQueue.cpp
index 037f347..23de338 100644
--- a/src/Vulkan/VkQueue.cpp
+++ b/src/Vulkan/VkQueue.cpp
@@ -209,6 +209,11 @@
 #ifndef __ANDROID__
 void Queue::present(const VkPresentInfoKHR* presentInfo)
 {
+	// This is a hack to deal with screen tearing for now.
+	// Need to correctly implement threading using VkSemaphore
+	// to get rid of it. b/132458423
+	waitIdle();
+
 	for(uint32_t i = 0; i < presentInfo->waitSemaphoreCount; i++)
 	{
 		vk::Cast(presentInfo->pWaitSemaphores[i])->wait();

src/Vulkan/libVulkan.cpp

diff --git a/src/Vulkan/libVulkan.cpp b/src/Vulkan/libVulkan.cpp
index 21b982d..eb5251c 100644
--- a/src/Vulkan/libVulkan.cpp
+++ b/src/Vulkan/libVulkan.cpp
@@ -2677,6 +2677,11 @@
 	TRACE("(VkQueue queue = %p, uint32_t waitSemaphoreCount = %d, const VkSemaphore* pWaitSemaphores = %p, VkImage image = %p, int* pNativeFenceFd = %p)",
 			queue, waitSemaphoreCount, pWaitSemaphores, image.get(), pNativeFenceFd);
 
+	// This is a hack to deal with screen tearing for now.
+	// Need to correctly implement threading using VkSemaphore
+	// to get rid of it. b/132458423
+	vkQueueWaitIdle(queue);
+
 	GrallocModule* grallocMod = GrallocModule::getInstance();
 	void* nativeBuffer;