package/sdl_net: update to latest git tree

The latest officially released version of SDL_net is 1.2.8, released
in 2012. Since then, there have been several bugfixes.

SDL's canonical source is now on GitHub. This commit points to the
SDL-1.2 branch from 15 Mar 2021.

Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
[yann.morin.1998@free.fr: use full-length commit hash]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/sdl_net/sdl_net.hash

@@ -1,3 +1,3 @@
 # Locally calculated
-sha256  5f4a7a8bb884f793c278ac3f3713be41980c5eedccecff0260411347714facb4  SDL_net-1.2.8.tar.gz
+sha256  7549dbc91813c37986300e7f34e63a068b42fd91abb41cabcaca63b4c7404ea5  SDL_net-620b0ba7dd84a0fdbd4cc8ef1b2be1cc10f90ae3.tar.gz
 sha256  e542f822a6cd82deccf82cf0f50192917b0158d725a6bc6348ab1ccdd890ecbe  COPYING

package/sdl_net/sdl_net.mk

@@ -4,8 +4,12 @@
 #
 ################################################################################
 
-SDL_NET_VERSION = 1.2.8
-SDL_NET_SITE = http://www.libsdl.org/projects/SDL_net/release
+# The latest officially released version of SDL_image is 1.2.8, released in 2012.
+# Since then, there have been several bugfixes.
+#
+# This commit points to the SDL-1.2 branch from 18 Feb 2021.
+SDL_NET_VERSION = 620b0ba7dd84a0fdbd4cc8ef1b2be1cc10f90ae3
+SDL_NET_SITE = $(call github,libsdl-org,SDL_net,$(SDL_NET_VERSION))
 SDL_NET_SOURCE = SDL_net-$(SDL_NET_VERSION).tar.gz
 SDL_NET_LICENSE = Zlib
 SDL_NET_LICENSE_FILES = COPYING