#47 Cinelerra 7, fix for compiler warnings in thirdparty/audiofile

[Mat Nieuwenhoven]

System Mint 18.3 (base: Ubuntu 16.04), 64 bit, AMD cpu, compiler 5.4.0 . The compiler gives warnings on 5 files about "incompatible implicit declaration of built-in function". This patch fixes it. Apply as "patch <thirdparty_audiofile.patch" in the thirdparty/audiofile directory.
Files affected: aiffwrite.c , aupv.c , openclose.c , track.c , util.c .