src/wav.c : Ensure all non-PCM files contain a 'fact' chunk.
src/wav.c : Ensure all non-PCM files contain a 'fact' chunk.

According to:

    http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html

all non-PCM formats must have a 'fact' chunk. This commit does two things:

* Add code to write a warning to the internal log file on file read/open if
  there is no 'fact' chunks.
* Add a 'fact' chunk on write as needed.

See: https://github.com/erikd/libsndfile/issues/70

erikd/libsndfile,libsndfile/libsndfile,audiokit/libsndfile,syb0rg/libsndfile,erikd/libsndfile,evpobr/libsndfile,Icenowy/libsndfile,evpobr/libsndfile,Icenowy/libsndfile,audiokit/libsndfile,evpobr/libsndfile,Icenowy/libsndfile,Icenowy/libsndfile,evpobr/libsndfile,libsndfile/libsndfile,libsndfile/libsndfile,syb0rg/libsndfile,RonNovy/libsndfile,erikd/libsndfile,audiokit/libsndfile,erikd/libsndfile,libsndfile/libsndfile,RonNovy/libsndfile,audiokit/libsndfile,syb0rg/libsndfile,RonNovy/libsndfile,Icenowy/libsndfile,syb0rg/libsndfile,evpobr/libsndfile,libsndfile/libsndfile,RonNovy/libsndfile,erikd/libsndfile