Replaced ENV.gcc_4_2 + comments with calls to "fails_with_llvm",
to specifically message to the user when a formula is known or suspected
to not build with LLVM. If the user specifies "--use-llvm", the message
will be displayed, but compilation will be tried anyway.
Since using LLVM is now an advanced/hidden feature instead of the
default on 10.6, we'll let the user try anyway (and submit patches
if things are now working.)
The CELT codec is a compression algorithm for audio. Like MP3, Vorbis,
and AAC it is suitable for transmitting music with high quality. Unlike
these formats CELT imposes very little delay on the signal, even less
than is typical for speech centric formats like Speex, GSM, or G.729.
