Allow Command Buffers to be allocated and freed

Added functionality so that the CommandPool can allocate and
free command buffer objects.

Bug b/119827933

Change-Id: I190ba3cd7738f2b5e37b196a0abba6d07cfae173
Reviewed-on: https://swiftshader-review.googlesource.com/c/22748
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>

src/Vulkan/VkCommandPool.hpp

diff --git a/src/Vulkan/VkCommandPool.hpp b/src/Vulkan/VkCommandPool.hpp
index 46b1426..05135c1 100644
--- a/src/Vulkan/VkCommandPool.hpp
+++ b/src/Vulkan/VkCommandPool.hpp
@@ -16,6 +16,7 @@
 #define VK_COMMAND_POOL_HPP_
 
 #include "VkObject.hpp"
+#include <set>
 
 namespace vk
 {
@@ -29,7 +30,11 @@
 
 	static size_t ComputeRequiredAllocationSize(const VkCommandPoolCreateInfo* pCreateInfo);
 
+	VkResult allocateCommandBuffers(VkCommandBufferLevel level, uint32_t commandBufferCount, VkCommandBuffer* pCommandBuffers);
+	void freeCommandBuffers(uint32_t commandBufferCount, const VkCommandBuffer* pCommandBuffers);
+
 private:
+	std::set<VkCommandBuffer>* commandBuffers;
 };
 
 static inline CommandPool* Cast(VkCommandPool object)