Added the ability to compile with luajit using --enable-luajit

configure.in

@@ -8,24 +8,29 @@ AC_PREFIX_DEFAULT([/usr])
 AC_PROG_LIBTOOL
 AC_PROG_CC
 AC_PROG_CXX
-AC_ARG_ENABLE([old-sdl], [  --enable-old-sdl   Enabled compatibility for older version of SDL, missing some defines],
-	AC_DEFINE([SDL_BUTTON_X1], 6, [Needed for old SDL versions])
-	AC_DEFINE([SDL_BUTTON_X2], 7, [Needed for old SDL versions])
-	AC_DEFINE([SDL_BUTTON_X1MASK], [SDL_BUTTON(SDL_BUTTON_X1)], [Needed for old SDL versions])
-	AC_DEFINE([SDL_BUTTON_X2MASK], [SDL_BUTTON(SDL_BUTTON_X2)], [Needed for old SDL versions])
-)
 AC_SEARCH_LIBS([sqrt], [m], [], AC_MSG_ERROR([Can't LÖVE without C math library]))
 AC_SEARCH_LIBS([SDL_Init], [SDL], [], AC_MSG_ERROR([Can't LÖVE without SDL]))
 AC_SEARCH_LIBS([glLoadIdentity], [GL], [], AC_MSG_ERROR([Can't LÖVE without OpenGL]))
 AC_SEARCH_LIBS([gluOrtho2D], [GLU], [], AC_MSG_ERROR([Can't LÖVE without OpenGL Utility Library]))
 AC_SEARCH_LIBS([alSourcePlay], [openal], [], AC_MSG_ERROR([Can't LÖVE without OpenAL]))
-AC_SEARCH_LIBS(
-	[lua_pcall],
-	[lua lua5.1],
-	if test "$ac_cv_search_lua_pcall" = "-llua5.1"; then
-		AC_SUBST([INCLUDE_LUA], [-I/usr/include/lua5.1])
-	fi,
-	AC_MSG_ERROR([Can't LÖVE without Lua])
+AC_ARG_ENABLE([luajit],
+	[  --enable-luajit Use LuaJIT instead of lua],
+	AC_SEARCH_LIBS(
+		[lua_pcall],
+		[luajit luajit-5.1],
+		if test "$ac_cv_search_lua_pcall" = "-lluajit5.1"; then
+			AC_SUBST([INCLUDE_LUA], [-I/usr/include/luajit-2.0])
+		fi,
+		AC_MSG_ERROR([Can't LÖVE without LuaJIT])
+	),
+	AC_SEARCH_LIBS(
+		[lua_pcall],
+		[lua lua5.1],
+		if test "$ac_cv_search_lua_pcall" = "-llua5.1"; then
+			AC_SUBST([INCLUDE_LUA], [-I/usr/include/lua5.1])
+		fi,
+		AC_MSG_ERROR([Can't LÖVE without Lua])
+	)
 )
 AC_SEARCH_LIBS([ilInit], [IL], [], AC_MSG_ERROR([Can't LÖVE without DevIL]))
 AC_SEARCH_LIBS([mng_initialize], [mng], [], AC_MSG_ERROR([DevIL needs MNG]))