Revert "src/sndfile.c : Make WAV/GSM610 with sample rates other than 8kHz invalid."

Commit was a0be1713b534a3ed3d02c0750669dc6d560b46d6.

Also revert the related commits:
* e4253e1609a7ab3f117427312c4d53a5bc7412c4
* 77504d6abde21d73505d32359ea0e5693835fda3