libjpeg: always use libjpeg_turbo

libjpeg_turbo is consistently built on Darwin now. I have no way to
verify FreeBSD so if anyone can confirm libjpeg_turbo is still broken
please revert this!

pkgs/development/libraries/libjpeg-turbo/default.nix

@@ -29,9 +29,6 @@ stdenv.mkDerivation rec {
     description = "A faster (using SIMD) libjpeg implementation";
     license = licenses.ijg; # and some parts under other BSD-style licenses
     maintainers = [ maintainers.vcunat ];
-    # upstream supports darwin (and others), but it doesn't build currently
     platforms = platforms.all;
-    hydraPlatforms = platforms.linux;
   };
 }
-

pkgs/top-level/all-packages.nix

@@ -10143,7 +10143,7 @@ with pkgs;
   libjpeg_original = callPackage ../development/libraries/libjpeg { };
   libjpeg_turbo = callPackage ../development/libraries/libjpeg-turbo { };
   libjpeg_drop = callPackage ../development/libraries/libjpeg-drop { };
-  libjpeg = if stdenv.isLinux then libjpeg_turbo else libjpeg_original; # some problems, both on FreeBSD and Darwin
+  libjpeg = libjpeg_turbo;
 
   libjreen = callPackage ../development/libraries/libjreen { };