Fix JNI package names in KtxTexture2.cpp

[Illithidek]

The name of the functions in the JNI KtxTexture2.cpp didn't match
the java package which cause linker error.

[CLAassistant]

All committers have signed the CLA.

[MarkCallow]

How come our tests were able to link and run?

[Illithidek]

Hey, tests just don't use these functions so JNI doesn't call them so the linker doesn't have a problem :)

[Illithidek]

Basically, JNI works on the promise that somewhere out there we will add a library that will have these functions. Like an "extern" in C. If something is not invoked then the promise doesn't have to be fulfilled.
All other functions works quite well, I found these by luck because I needed to use "needsTranscoding" and a linker error appeared.

[MarkCallow]

Thanks for the contribution.