1. glTexImage*D does not accept compressed formats.
2. Replacing it with glCompressedTexImage*D is not an option as per GLES 2.0 spec
since passing null data is not allowed.
3. glCompressedTexSubImage*D must always be preceded by a glCompressedTexImage*d
(or glTexStorage*D) call.
4. Therefore the only way is to do nothing in allocateStorage() and switch to
glCompressedTexImage*D in setCompressedData() whenever mutable storage is in use.
This makes ETC1 textures working on the Beaglebone (and presumably others).
Change-Id: I21a040f6ed4aecaa494b6e5a6c6cd75b7389c15c
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
87666d391c