Cleanup: gcc7.1 warnings

source/blender/editors/transform/transform_input.c

@@ -187,7 +187,7 @@ static void InputAngle(TransInfo *UNUSED(t), MouseInput *mi, const double mval[2
 	/* use doubles here, to make sure a "1.0" (no rotation) doesn't become 9.999999e-01, which gives 0.02 for acos */
 	double deler = (((dx1 * dx1 + dy1 * dy1) +
 	                 (dx2 * dx2 + dy2 * dy2) -
-	                 (dx3 * dx3 + dy3 * dy3)) / (2.0 * ((A * B) ? (A * B) : 1.0)));
+	                 (dx3 * dx3 + dy3 * dy3)) / (2.0 * (((A * B) != 0.0) ? (A * B) : 1.0)));
 	/* ((A * B) ? (A * B) : 1.0) this takes care of potential divide by zero errors */
 
 	float dphi;