It looks like #7 didn't update CMakeLists.txt properly - defines
specified with -D have to be added as compile definitions.
Additionally, -O3 must be specified redundantly as a compile option and
as a link option - compile option makes .wasm bits small & fast, and
link option enables JS minifier.
After this fix CMake build results in minimal js/wasm files as well.
This change makes it possible to exclude formats using compile time
options. BC7 is *never* exposed on the web and it has an absolutely huge
coding table which means we're just wasting space.
basis_transcoder.js 58707
basis_transcoder.wasm 224404
