sdl_net: add hash file

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

package/sdl_net/sdl_net.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256	5f4a7a8bb884f793c278ac3f3713be41980c5eedccecff0260411347714facb4	SDL_net-1.2.8.tar.gz