SDL_net: fix-up installed headers

Patch submitted by Jan Malakhovski <oxij@oxij.org>.

pkgs/development/libraries/SDL_net/default.nix

@@ -13,7 +13,16 @@ stdenv.mkDerivation rec {
 
   propagatedBuildInputs = [SDL];
 
-  postInstall = "ln -s $out/include/SDL/SDL_net.h $out/include/";
+  postInstall = ''
+    sed -i -e 's,"SDL.h",<SDL/SDL.h>,' \
+    -e 's,"SDL_endian.h",<SDL/SDL_endian.h>,' \
+    -e 's,"SDL_version.h",<SDL/SDL_version.h>,' \
+    -e 's,"begin_code.h",<SDL/begin_code.h>,' \
+    -e 's,"close_code.h",<SDL/close_code.h>,' \
+      $out/include/SDL/SDL_net.h
+
+    ln -sv $out/include/SDL/SDL_net.h $out/include/
+  '';
 
   meta = {
     description = "SDL networking library";