Memory leak of m_paucEncodingBits in Etc::Image

[C0lumbo]

In Image::~Image, the code to free m_paucEncodingBits is commented out. Presumably this is because one of the Image::Image constructors allows the caller to pass in their own encoding bits so calling delete[] would be unsafe in this scenario. However, in other codepaths, the class allocates it's own m_paucEncodingBits in the Image::Encode function which is never freed.

A possible solution would be to add a bool to Etc::Image to track whether or not it allocated m_paucEncodingBits, and free when necessary.

[C0lumbo]

Actually looking at the behaviour of Etc::EncodeMipmaps Etc::Encode it's clear that m_paucEncodingBits must persist beyond the lifetime of the Etc::Image so it's the callers responsibility to free the memory. Perhaps that could be made clearer somehow, but there's no bug.