netbsd.libossaudio: fix build
netbsd.libossaudio: fix build

The file this was trying to modify doesn't even exist.

Tested by building pkgsCross.x86_64-netbsd.netbsd.libossaudio from
x86_64-linux.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs