fix a few more warnings under Windows

fix linker issue due to unsigned/int variable

Demos/SoftDemo/SoftDemo.h

@@ -148,7 +148,7 @@ public:\
 	static DemoApplication* Create()\
 	{\
 		SoftDemo* demo = new SoftDemo##a;\
-		extern unsigned int current_demo;\
+		extern int current_demo;\
 		current_demo=a;\
 		demo->myinit();\
 		demo->initPhysics();\

Demos/ThreadingDemo/main.cpp

@@ -93,7 +93,7 @@ void	SampleThreadFunc(void* userPtr,void* lsMemory)
 		}
 		//do some fake work
 		for (int i=0;i<1000000;i++)
-			args->m_fakeWork = 1.21*args->m_fakeWork;
+			args->m_fakeWork = btScalar(1.21)*args->m_fakeWork;
 		workLeft = count>0;
 	}
 	printf("finished\n");