haproxy: Update HAProxy to v2.1.2

- Major version jump from v2.0 to v2.1
- Update haproxy download URL and hash
- Add new patches (see https://www.haproxy.org/bugs/bugs-2.1.2.html)
- Stop building LUA 5.3 in the haproxy build-process and use liblua5.3 as a dependency instead

Signed-off-by: Christian Lachner <gladiac@gmail.com>

net/haproxy/patches/050-MINOR-lua-Add-hlua_prepend_path-function.patch

@@ -0,0 +1,38 @@
+commit ed5d6a9f3c2a1cf9e0408c438c76c0643df9d6a5
+Author: Tim Duesterhus <tim@bastelstu.be>
+Date:   Sun Jan 12 13:55:39 2020 +0100
+
+    MINOR: lua: Add hlua_prepend_path function
+    
+    This function is added in preparation for following patches.
+    
+    (cherry picked from commit c9fc9f2836f1e56eef3eaf690421eeff34dd8a2b)
+    Signed-off-by: Willy Tarreau <w@1wt.eu>
+
+diff --git a/src/hlua.c b/src/hlua.c
+index 37f786687..10d615211 100644
+--- a/src/hlua.c
++++ b/src/hlua.c
+@@ -7458,6 +7458,22 @@ static int hlua_load(char **args, int section_type, struct proxy *curpx,
+ 	return 0;
+ }
+ 
++/* Prepend the given <path> followed by a semicolon to the `package.<type>` variable
++ * in the given <ctx>.
++ */
++static int hlua_prepend_path(struct hlua ctx, char *type, char *path)
++{
++	lua_getglobal(ctx.T, "package"); /* push package variable   */
++	lua_pushstring(ctx.T, path);     /* push given path         */
++	lua_pushstring(ctx.T, ";");      /* push semicolon          */
++	lua_getfield(ctx.T, -3, type);   /* push old path           */
++	lua_concat(ctx.T, 3);            /* concatenate to new path */
++	lua_setfield(ctx.T, -2, type);   /* store new path          */
++	lua_pop(ctx.T, 1);               /* pop package variable    */
++
++	return 0;
++}
++
+ /* configuration keywords declaration */
+ static struct cfg_kw_list cfg_kws = {{ },{
+ 	{ CFG_GLOBAL, "lua-load",                 hlua_load },