Don't store orientation in exported image

this causes double rotation in viewers that support the rotation metadata.

postprocess.c

@@ -189,10 +189,6 @@ create_exif(struct Imagedata data)
     entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_SOFTWARE);
     exif_set_string(entry, data.software, strlen(data.software));
 
-    // Orientation
-    entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_ORIENTATION);
-    exif_set_short(entry->data, EXIF_BYTE_ORDER_INTEL, data.orientation);
-
     // Various datetime fields
     entry = init_tag(exif, EXIF_IFD_EXIF, EXIF_TAG_DATE_TIME);
     exif_set_string(entry, data.datetime, strlen(data.datetime));