[opus] [libopusfile PATCH] build: implement autotools build system for libopusfile.

[Timothy B. Terriberry]

Diego Elio Pettenò wrote:
> This includes the check target that Tim requested.

Thanks for that. Right now (using autogen.sh copied from libopus), I am 
getting:

autoheader-2.68: error: AC_CONFIG_HEADERS not found in configure.ac