MEDIUM: lua: use the Lua-5.3 version of the library

The Lua-5.3 version of the library adds a required function to fix
a bug with the forced-yield system.

This patch permits to build with the Lua-5.3 library. Main changes
are:
 - "unsigned" type disappear to be replaced by signed type,
 - prototype of the yield function callback changes.
diff --git a/Makefile b/Makefile
index 06288c1..1a31792 100644
--- a/Makefile
+++ b/Makefile
@@ -78,7 +78,7 @@
 #   LUA_LIB        : force the lib path to lua
 #   LUA_INC        : force the include path to lua
 #   LUA_LIB_NAME   : force the lib name (or automatically evaluated, by order of
-#                                        priority : lua5.2, lua52, lua).
+#                                        priority : lua5.3, lua53, lua).
 #   IGNOREGIT      : ignore GIT commit versions if set.
 #   VERSION        : force haproxy version reporting.
 #   SUBVERS        : add a sub-version (eg: platform, model, ...).