[3.6] remote note about IRIX in aifc (#3304)

This comment hasn't been true since Python 3.0.
(cherry picked from commit b84efddb9a87d515029bac943812b66eb3486eb5)

Doc/library/aifc.rst

@@ -18,12 +18,6 @@ AIFF is Audio Interchange File Format, a format for storing digital audio
 samples in a file.  AIFF-C is a newer version of the format that includes the
 ability to compress the audio data.
 
-.. note::
-
-   Some operations may only work under IRIX; these will raise :exc:`ImportError`
-   when attempting to import the :mod:`cl` module, which is only available on
-   IRIX.
-
 Audio files have a number of parameters that describe the audio data. The
 sampling rate or frame rate is the number of times per second the sound is
 sampled.  The number of channels indicate if the audio is mono, stereo, or