Changed BulletMultiThreaded Thread Support to be passed in, rather then global 'Win32ThreadSupport'/'Libspe2ThreadSupport' etc.

This allows developer to hookup Bullet to a custom task scheduler, by deriving from btThreadSupportInterface.

Extras/BulletMultiThreaded/btThreadSupportInterface.h

@@ -0,0 +1,42 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2007 Erwin Coumans  http://bulletphysics.com
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef THREAD_SUPPORT_INTERFACE_H
+#define THREAD_SUPPORT_INTERFACE_H
+
+
+//#include <LinearMath/btScalar.h> //for uint32_t etc.
+#include "PlatformDefinitions.h"
+
+class btThreadSupportInterface
+{
+public:
+
+	virtual ~btThreadSupportInterface();
+
+///send messages to SPUs
+	virtual void sendRequest(uint32_t uiCommand, uint32_t uiArgument0, uint32_t uiArgument1) =0;
+
+///check for messages from SPUs
+	virtual	void waitForResponse(unsigned int *puiArgument0, unsigned int *puiArgument1) =0;
+
+///start the spus (can be called at the beginning of each frame, to make sure that the right SPU program is loaded)
+	virtual	void startSPU() =0;
+
+///tell the task scheduler we are done with the SPU tasks
+	virtual	void stopSPU()=0;
+};
+
+#endif //THREAD_SUPPORT_INTERFACE_H