Consistently use doubles to calculate the inverse scale factors
Consistently use doubles to calculate the inverse scale factors

Use of floats here triggered a bug in the gcc 4.3 soft-float code. Since
we are already using 1.0/scale in some places, it seems OK to make this
consistent.

DirectFB/directfb,sklnet/DirectFB,kevleyski/directfb,deniskropp/DirectFB,DirectFB/directfb,jcdubois/DirectFB,mtsekm/test,djbclark/directfb-core-DirectFB,lancebaiyouview/DirectFB,kaostao/directfb,Distrotech/DirectFB,kevleyski/directfb,kevleyski/DirectFB-1,sklnet/DirectFB,kevleyski/directfb,kevleyski/DirectFB-1,djbclark/directfb-core-DirectFB,djbclark/directfb-core-DirectFB,lancebaiyouview/DirectFB,dfbdok/DirectFB1,djbclark/directfb-core-DirectFB,mtsekm/test,sklnet/DirectFB,deniskropp/DirectFB,DirectFB/directfb,deniskropp/DirectFB,jcdubois/DirectFB,Distrotech/DirectFB,sklnet/DirectFB,kaostao/directfb,dfbdok/DirectFB1,jcdubois/DirectFB,lancebaiyouview/DirectFB,kevleyski/directfb,Distrotech/DirectFB,mtsekm/test,lancebaiyouview/DirectFB,kevleyski/DirectFB-1,kevleyski/DirectFB-1,dfbdok/DirectFB1,deniskropp/DirectFB,kaostao/directfb