Fix issues in de::ThreadSafeRingBuffer<>
Fix issues in de::ThreadSafeRingBuffer<>

 * Use size_t for size-like values
 * Use std::vector<> for memory lifetime management

Change-Id: Idaf621829df4608968e7d8f3e60b7f3c948f0b04

chadversary/deqp,KhronosGroup/Vulkan-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,googlestadia/VK-GL-CTS,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,KhronosGroup/VK-GL-CTS,KhronosGroup/Vulkan-CTS,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/VK-GL-CTS,KhronosGroup/VK-GL-CTS,chadversary/deqp,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS,KhronosGroup/Vulkan-CTS,googlestadia/VK-GL-CTS,KhronosGroup/Vulkan-CTS