* q_sound.h: add WAV_FORMAT_PCM as a new macro, defined as 1.
* snd_mem.c (S_LoadSound): use WAV_FORMAT_PCM. reject wav files which are
neither 8 nor 16 bit. reject wav files which have zero samples. report
the wav file name with the error messages so that they mean something.
git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@350 af15c1b1-3010-417e-b628-4374ebc0bcbd