misc video players: Clean up cross

pkgs/development/libraries/ffmpeg/generic.nix

@@ -79,7 +79,10 @@ stdenv.mkDerivation rec {
     ++ optional (reqMin "1.0") "doc" ; # just dev-doc
   setOutputFlags = false; # doesn't accept all and stores configureFlags in libs!
 
+  configurePlatforms = [];
   configureFlags = [
+      "--arch=${hostPlatform.parsed.cpu.name}"
+      "--target_os=${hostPlatform.parsed.kernel.name}"
     # License
       "--enable-gpl"
       "--enable-version3"
@@ -145,6 +148,9 @@ stdenv.mkDerivation rec {
       "--disable-stripping"
     # Disable mmx support for 0.6.90
       (verFix null "0.6.90" "--disable-mmx")
+  ] ++ optionals (stdenv.hostPlatform == stdenv.buildPlatform) [
+      "--cross-prefix=${stdenv.cc.targetPrefix}"
+      "--enable-cross-compile"
   ] ++ optional stdenv.cc.isClang "--cc=clang";
 
   nativeBuildInputs = [ perl pkgconfig texinfo yasm ];
@@ -168,18 +174,6 @@ stdenv.mkDerivation rec {
     moveToOutput share/ffmpeg/examples "$doc"
   '';
 
-  /* Cross-compilation is untested, consider this an outline, more work
-     needs to be done to portions of the build to get it to work correctly */
-  crossAttrs = {
-    configurePlatforms = [];
-    configureFlags = configureFlags ++ [
-      "--cross-prefix=${stdenv.cc.targetPrefix}"
-      "--enable-cross-compile"
-      "--target_os=${hostPlatform.parsed.kernel.name}"
-      "--arch=${hostPlatform.parsed.cpu.name}"
-    ];
-  };
-
   installFlags = [ "install-man" ];
 
   passthru = {