neutrino: add luajit

Luajit is a dynamic scripting language completely compatible to lua 5.1. the whole VM has been rewritten from the ground up
and is relentlessly optimized for performance. It combines a high-speed interpreter, written in assembler, with a state-of-the-art JIT compiler.
A substantial reduction of the overhead associated with dynamic languages allows it to break into the performance range traditionally reserved for offline,
static language compilers.

https://luajit.org/luajit.html
https://github.com/LuaJIT/LuaJIT/tree/master

There was additional code needed to enable neutrino to compile against lua 5.1. This was mostly taken from the luaposix compat-headers.
There are still some minor issue that will be easy to fix but it's up and running so damn fast!

Signed-off-by: Markus Volk <f_l_k@t-online.de>

src/gui/lua/lua_threads.h

@@ -31,12 +31,17 @@ extern "C"
 #include <lualib.h>
 }
 #include <pthread.h>
+#include <config.h>
 
 /* wrap strerror_r(). */
 #ifndef strerror_r
 #define strerror_r __strerror_r
 #endif
 
+#if LUA_COMPAT_5_2
+void lua_rawsetp (lua_State *L, int i, const void *p);
+#endif
+
 #define OS_THREAD_RETURN void *
 #define INFINITE_JOIN_TIMEOUT -1
 #define JOIN_OK 0