Fix image scaling with masks (bug#38109)
* src/image.c (lookup_image): Move call to image_set_transform after postprocess_image. (image_create_x_image_and_pixmap_1): Use new function. (image_set_transform): Apply the transform to the mask too. (x_create_xrender_picture): New function. (Create_Pixmap_From_Bitmap_Data): (xpm_load): Use new function. * src/xterm.c (x_composite_image): Use PictOpOver when there is a mask so the transparency is honoured. (x_draw_image_foreground_1): Use x_composite_image.