[opus] libopusfile

[Timothy B. Terriberry]

Diego Elio Pettenò wrote:
> With my Gentoo Linux hat on I'd argue strongly for providing autotools,
> for Unix at least. It makes our job extremely simpler, especially as of
> right now the makefile does not support cross-compilation.

A request, if I may: libtheora's autotools support included a "make 
debug" target which built things with debug info and disabled all 
optimizations. I would find a similar thing for libopusfile (that also 
enabled assertions) very useful. Right now the Makefile does this by 
default (you have to edit it by hand to enable optimization at all), but 
that's obviously now how things should be shipped to end-users.