lua_include: fix lua_raw{get,set}p functions for Lua 5.1

Previous implementations of these functions caused LuaJIT to crash with
  lj_api.c:49: index2adr: Assertion `fn->c.gct == ~(~8u) && !((fn)->c.ffid== 0)' failed.

Use the implementation by Hisham Muhammad (see https://github.com/hishamhm/lua-compat-5.2)