Fix crash in oiiotool --resize with multi-subimages (#2711)
Fix crash in oiiotool --resize with multi-subimages (#2711)

This was subtle. Empty subimage include/exclude specifications would
confuse compute_subimages(), which in turn would MUCH later do a
mis-allocation and lead to a situation in --resize where it would
iterate over subimages that had not need allocated.

Signed-off-by: Larry Gritz <f0a1ce6f80112d72f7276457fd261d671b827567@larrygritz.com>
lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio