Add note about nonfree license of libfaac.

Originally committed as revision 18735 to svn://svn.ffmpeg.org/ffmpeg/trunk

LICENSE

@@ -23,9 +23,10 @@ Some external libraries, e.g. libx264, are under GPL and can be used in
 conjunction with FFmpeg. They require --enable-gpl to be passed to configure
 as well.
 
-The nonfree external libraries libamrnb and libamrwb can be hooked up in FFmpeg.
-You need to pass --enable-nonfree to configure to enable them. Employ this
-option with care as FFmpeg then becomes nonfree and unredistributable.
+The nonfree external libraries libamrnb, libamrwb and libfaac can be hooked up
+in FFmpeg. You need to pass --enable-nonfree to configure to enable them. Employ
+this option with care as FFmpeg then becomes nonfree and unredistributable.
+Note that libfaac claims to be LGPL, but is not.
 
 There are a handful of files under other licensing terms, namely: