mhook: Fixes to make Mhook_Unhook() work.
mhook: Fixes to make Mhook_Unhook() work.

This fixes ListRemove() when deleting the last trampoline in a
list, and fixes TrampolineGet() so it can find trampolines.

https://github.com/martona/mhook/pull/3

schulmar/apitrace,schulmar/apitrace,apitrace/apitrace,schulmar/apitrace,schulmar/apitrace,schulmar/apitrace,apitrace/apitrace,apitrace/apitrace,apitrace/apitrace