Revert "Fix T42222"

This reverts commit 507712db3f.

Error was quite an old compiler, which had further warnings/errors.

Old compilers can just have this defined in BLI_math

source/blender/editors/interface/view2d_ops.c

@@ -1726,7 +1726,7 @@ static void scroller_activate_apply(bContext *C, wmOperator *op)
 	temp = vsm->fac * vsm->delta;
 
 	/* round to pixel */
-	temp = floorf(temp / vsm->fac_round + 0.5f) * vsm->fac_round;
+	temp = roundf(temp / vsm->fac_round) * vsm->fac_round;
 	
 	/* type of movement */
 	switch (vsm->zone) {