New function 'setCstacklimit'

Added new functions to dynamically set the C-stack limit
('lua_setCstacklimit' in the C-API, 'debug.setCstacklimit' in Lua).

lua.h

@@ -462,6 +462,7 @@ LUA_API lua_Hook (lua_gethook) (lua_State *L);
 LUA_API int (lua_gethookmask) (lua_State *L);
 LUA_API int (lua_gethookcount) (lua_State *L);
 
+LUA_API int (lua_setCstacklimit) (lua_State *L, unsigned int limit);
 
 struct lua_Debug {
   int event;