Fix reading of images using PixelRegion with ranges ending before the limit. * __magick_read__.cc (calculate_region): reduce image cache being loaded into memory by checking max() instead of limit(). Simplify calculation of output size by using nelem(). Fix calculation of the pointer shift required when moving to next column in cases where limit() and max () were different.

5a51fb7777a9950502965a043a70bd6ca5e0498b gnulib-hg