pkgs/development/libraries/audio: enable build on darwin

pkgs/development/libraries/audio/libsmf/default.nix

···
     homepage = "https://github.com/stump/libsmf";
     license = licenses.bsd2;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/lilv/default.nix

···
     description = "A C library to make the use of LV2 plugins";
     license = licenses.mit;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/lvtk/default.nix

···
     homepage = "https://lvtk.org/";
     license = licenses.gpl3;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/qm-dsp/default.nix

···
     homepage = "https://code.soundsoftware.ac.uk/projects/qm-dsp";
     license = licenses.gpl2Plus;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/raul/default.nix

···
     homepage = "http://drobilla.net/software/raul";
     license = licenses.gpl3;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/sratom/default.nix

···
     description = "A library for serialising LV2 atoms to/from RDF";
     license = licenses.mit;
     maintainers = [ maintainers.goibhniu ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/audio/vamp-plugin-sdk/default.nix

···
     homepage = "https://vamp-plugins.org/";
     license = licenses.bsd3;
     maintainers = [ maintainers.goibhniu maintainers.marcweber ];
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/development/libraries/libkeyfinder/default.nix pkgs/development/libraries/audio/libkeyfinder/default.nix

···
     description = "Musical key detection for digital audio (C++ library)";
     homepage = "https://mixxxdj.github.io/libkeyfinder/";
     license = licenses.gpl3Plus;
-    platforms = platforms.linux;
+    platforms = platforms.unix;
   };
 }

pkgs/top-level/all-packages.nix

···
 
   libkate = callPackage ../development/libraries/libkate { };
 
-  libkeyfinder = callPackage ../development/libraries/libkeyfinder { };
+  libkeyfinder = callPackage ../development/libraries/audio/libkeyfinder { };
 
   libkml = callPackage ../development/libraries/libkml { };