Remove stuff from /extra/ and the JPEG transcoding file from compilation, as
we don't need them.
A disable define for box decoding is also added, but currently commented out as
there's no need to disable the function right now.
Co-authored-by: Moonchild <moonchild@palemoon.org>
Fixes building on Windows.
I also decided to move the preprocessed jxl/version.h to our include/jxl
instead of relying on moz.build in preprocessing the file. Future me
should note to not forget to update the version number at that new file
highway upstream added a new header file to be included in highway.h after
0.15.0 it seems, so we have to account for that in moz.build.
Also brought back allowing compiler warnings for libjxl and highway.
Apparently the equivalent of AllowCompilerWarnings() is a bool whose name
is UPPERCASE and uses under_scores instead of CamelCase.
