Work around LuaJIT issues on aarch64 (#9614)

- Move the text segment below the 47-bit limit, needed for script_exception_wrapper which must be lightuserdata
- Replace CUSTOM_RIDX_SCRIPTAPI with full userdata

src/script/common/c_internal.h

@@ -54,6 +54,15 @@ extern "C" {
 #define CUSTOM_RIDX_CURRENT_MOD_NAME    (CUSTOM_RIDX_BASE + 2)
 #define CUSTOM_RIDX_BACKTRACE           (CUSTOM_RIDX_BASE + 3)
 
+// Determine if CUSTOM_RIDX_SCRIPTAPI will hold a light or full userdata
+#if defined(__aarch64__) && USE_LUAJIT
+/* LuaJIT has a 47-bit limit for lightuserdata on this platform and we cannot
+ * assume that the ScriptApi class was allocated at a fitting address. */
+#define INDIRECT_SCRIPTAPI_RIDX 1
+#else
+#define INDIRECT_SCRIPTAPI_RIDX 0
+#endif
+
 // Pushes the error handler onto the stack and returns its index
 #define PUSH_ERROR_HANDLER(L) \
 	(lua_rawgeti((L), LUA_REGISTRYINDEX, CUSTOM_RIDX_BACKTRACE), lua_gettop((L)))