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>

configure.ac

@@ -261,19 +261,20 @@ AC_ARG_ENABLE(lua,
 
 if test "$enable_lua" = "yes"; then
 	AC_DEFINE(ENABLE_LUA, 1, [include Lua support])
-	PKG_CHECK_MODULES([LUA], [lua >= 5.2], [
-		echo "lua >= 5.2 found"
-	], [
-		PKG_CHECK_MODULES([LUA], [lua5.2 >= 5.2], [
-			echo "lua5.2 found"
-		], [
+	PKG_CHECK_MODULES(LUA, lua, LLUA="yes", LLUA="no")
+	PKG_CHECK_MODULES(luajit, luajit, LLUAJIT="yes", LLUAJIT="no")
+		if test "x$LLUAJIT" = "xyes"; then
+			LUA_LIBS="-lluajit-5.1"
+			AC_DEFINE(LUA_COMPAT_5_2, 1, [needed for build with lua 5.1])
+		elif test "x$LLUA" = "xyes"; then
+			LUA_LIBS="-llua"
+			AC_DEFINE(LUA_COMPAT_5_2, 0, [needed for build with lua 5.1])
+		else
 			echo "lualib not found, assuming static lua in linker path..."
 			LUA_LIBS="-llua -ldl"
 			AC_DEFINE(STATIC_LUAPOSIX, 1, [Define to 1 for static lua build.])
-		])
-	])
-	# hack...
-	AC_DEFINE(LUA_COMPAT_5_2, 1, [does not really belong in config.h, but is needed for build with lua 5.3+])
+			AC_DEFINE(LUA_COMPAT_5_2, 0, [needed for build with lua 5.1])
+		fi
 fi
 AM_CONDITIONAL(ENABLE_LUA, test "$enable_lua" = "yes")
 

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

src/gui/lua/lua_video.h

@@ -20,6 +20,10 @@
 #ifndef _LUAVIDEO_H
 #define _LUAVIDEO_H
 
+#if LUA_COMPAT_5_2
+void lua_rawsetp (lua_State *L, int i, const void *p);
+#endif
+
 class CLuaVideo
 {
 	public:

src/gui/lua/luainstance.cpp

@@ -1245,4 +1245,41 @@ int CLuaInstance::scale2Res(lua_State *L)
 	return 1;
 }
 
+#if LUA_COMPAT_5_2
+
+void lua_pushunsigned (lua_State *L, lua_Unsigned n) {
+  lua_pushnumber(L, lua_unsigned2number(n));
+}
+
+
+lua_Unsigned luaL_checkunsigned (lua_State *L, int i) {
+  lua_Unsigned result;
+  lua_Number n = lua_tonumber(L, i);
+  if (n == 0 && !lua_isnumber(L, i))
+    luaL_checktype(L, i, LUA_TNUMBER);
+  lua_number2unsigned(result, n);
+  return result;
+}
+
+int lua_absindex (lua_State *L, int i) {
+  if (i < 0 && i > LUA_REGISTRYINDEX)
+    i += lua_gettop(L) + 1;
+  return i;
+}
+
+void lua_rawgetp (lua_State *L, int i, const void *p) {
+  int abs_i = lua_absindex(L, i);
+  lua_pushlightuserdata(L, (void*)p);
+  lua_rawget(L, abs_i);
+}
+
+void lua_rawsetp (lua_State *L, int i, const void *p) {
+  int abs_i = lua_absindex(L, i);
+  luaL_checkstack(L, 1, "not enough stack slots");
+  lua_pushlightuserdata(L, (void*)p);
+  lua_insert(L, -2);
+  lua_rawset(L, abs_i);
+}
+
+#endif
 /* --------------------------------------------------------------- */

src/gui/lua/luainstance_helpers.h

@@ -23,6 +23,31 @@
 
 #include <map>
 
+#if LUA_COMPAT_5_2
+
+#include <stdint.h>
+#include <math.h>
+
+typedef uint32_t lua_Unsigned;
+int lua_absindex (lua_State *L, int i);
+void lua_rawgetp (lua_State *L, int i, const void *p);
+void lua_rawsetp (lua_State *L, int i, const void *p);
+void lua_pushunsigned (lua_State *L, lua_Unsigned n);
+lua_Unsigned luaL_checkunsigned (lua_State *L, int i);
+#define lua_pushglobaltable(L) \
+	lua_pushvalue(L, LUA_GLOBALSINDEX)
+
+#define LUA_SUPUNSIGNED \
+	((lua_Number)(~(lua_Unsigned)0) + 1)
+
+#define lua_number2unsigned(i,n) \
+	((i) = (lua_Unsigned)(n))
+
+#define lua_unsigned2number(u) \
+	(((u) <= (lua_Unsigned)INT_MAX) ? (lua_Number)(int)(u) : (lua_Number)(u))
+
+#endif
+
 //#define LUA_DEBUG printf
 #define LUA_DEBUG(...)