More double-check locking

[Aaron Tomb]

I've done another small run of the double-check locking detector against
the Mono class libraries, and have another list of methods probably
worth looking at.

Apparently real
---------------
System.Windows.Forms.XplatUIOSX::GetMessage
System.Web.Compilation.CachingCompiler::Compile (both instances)
System.Web.Configuration.WebControlsConfig::get_Instance
System.Web.UI.WebControls.FontUnitConverter::GetStandardValues
System.Web.CapabilitiesLoader::Init
System.Web.HttpApplicationFactory::Dispose
System.Web.HttpApplicationFactory::GetInstance
System.Web.HttpRuntime::InternalExecuteRequest
System.Web.Services.Configuration.WSConfig::get_Instance

False alarms?
-------------
System.Windows.Forms.XplatUIX11::SetWMStyles
System.Windows.Forms.XplatUIX11::SetWindowState
System.Runtime.Remoting.Channels.RemotingThreadPool::RunThread

Unsure
------
System.Web.QueueManager::GetNextRequest

I hope this is helpful.

Aaron