Undo Bullet double define, see https://www.panda3d.org/forums/viewtopic.php?p=88420#88420

panda/src/bullet/bullet_includes.h

@@ -17,10 +17,6 @@
 
 #include "pandabase.h"
 
-#ifdef STDFLOAT_DOUBLE
-#define BT_USE_DOUBLE_PRECISION 1
-#endif
-
 #include "btBulletDynamicsCommon.h"
 
 #ifndef CPPPARSER