Simplify the locking strategy for Module and its owned objects to always use the Module's mutex to avoid A/B deadlocks. We had a case where a symbol vendor was locking itself and then calling a function that would try to get it's Module's mutex and at the same time another thread had the Module mutex that was trying to get the SymbolVendor mutex. Now any classes that inherit from ModuleChild should use the module lock using code like:

void
ModuleChildSubclass::Function
{
	ModuleSP module_sp(GetModule());
	if (module_sp)
	{
    	lldb_private::Mutex::Locker locker(module_sp->GetMutex());
		... do work here...
	}
}

This will help avoid deadlocks by using as few locks as possible for a module and all its child objects and also enforce detecting if a module has gone away (the ModuleSP will be returned empty if the weak_ptr does refer to a valid object anymore).

llvm-svn: 152679