Corrected an issue in the HPMHookGen when interfaces only have one membe...

Corrected an issue in the HPMHookGen when interfaces only have one member

This fixed the `use strict` workaround in commit 8b7ae80d0c08e1502f6d3b29b60dd8974f759415

The error was happening because the `inter_quest` interface currently only contains one member, and the xml parser would compact the generated xml tree. This commit enforces a stricter tree structure, so that it works regardless of the number of entries.