use dontBuild instead of hacks

changes:
 * buildPhase = "true"
 * buildPhase = ":"

pkgs/development/libraries/fmod/4.24.16.nix

@@ -29,11 +29,10 @@ stdenv.mkDerivation rec {
 
   dontStrip = true;
   dontPatchELF = true;
+  dontBuild = true;
 
   makeFlags = [ "DESTLIBDIR=$(out)/lib" "DESTHDRDIR=$(out)/include" ];
 
-  buildPhase = "true";
-
   preInstall = ''
     mkdir -p $out/lib
   '';

pkgs/development/libraries/fmod/default.nix

@@ -18,7 +18,8 @@ stdenv.mkDerivation rec {
   };
 
   dontStrip = true;
-  buildPhase = "true";
+  dontBuild = true;
+
   installPhase = ''
     mkdir -p $out/lib $out/include/fmodex