Synchronize joystick events between all ports

Generate wxJoystickEvent with the same fields under all platforms by
making the Linux and macOS versions follow MSW convention of using
"1 << N" for the changed button.

Add GetButtonOrdinal() accessor which can be used to retrieve just N.

Closes #18233.

include/wx/math.h

@@ -181,4 +181,14 @@ inline double wxRadToDeg(double rad) { return (rad * 180.0) / M_PI; }
 /* Compute the greatest common divisor of two positive integers */
 WXDLLIMPEXP_BASE unsigned int wxGCD(unsigned int u, unsigned int v);
 
+#ifdef __cplusplus
+/* Count trailing zeros
+
+Returns the number of trailing zeros in unsigned input x.
+
+@since 3.1.2
+*/
+WXDLLIMPEXP_BASE unsigned int wxCTZ(unsigned x);
+#endif
+
 #endif /* _WX_MATH_H_ */