Qt should load libvulkan.so.1, not libvulkan.so

Qt is dynamically loading libvulkan.so on runtime, users have to install not only libvulkan1 but also libvulkan-dev if they want to use any application that use Qt Vulkan.

According to Linux convention, libvulkan.so is for development and should not be considered always installed on end-user's environment. Qt should dlopen "libvulkan.so.1" in runtime.