add the BT_ prefix for all #ifdef guards, to avoid conflicts with developers own header defines.

Fixes Issue 497

//license header
#ifndef BT_RIGIDBODY_H
#define BT_RIGIDBODY_H
class btRigidBody
{
};
#endif //BT_RIGIDBODY_H

src/LinearMath/btQuickprof.h

@@ -12,8 +12,8 @@
 
 
 
-#ifndef QUICK_PROF_H
-#define QUICK_PROF_H
+#ifndef BT_QUICK_PROF_H
+#define BT_QUICK_PROF_H
 
 //To disable built-in profiling, please comment out next line
 //#define BT_NO_PROFILE 1
@@ -191,6 +191,6 @@ public:
 
 
 
-#endif //QUICK_PROF_H
+#endif //BT_QUICK_PROF_H