Add XInitThreads
Add XInitThreads

New Vulkan requirement: Vulkan apps using XLib must acall XInitThreads.
renelindsay/WSIWindow,renelindsay/WSIWindow,renelindsay/Vulkan-WSIWindow,renelindsay/Vulkan-WSIWindow,renelindsay/WSIWindow,renelindsay/Vulkan-WSIWindow