Always perform signature searches on an unaltered copy of the binary. This avoids signature mismatches if the same function is detoured twice and thus the first bytes of the function were replaced by the detour.
* Add basic Insurgency support on Windows x64
This allows SourceMod to load on x64 Insurgency. There are still a lot of variable truncation warnings that have to be dealt with.
* Fix 32bit builds
* Compile MySQL extension as well
The hack for __iob_func being removed from the core runtime, but required by the old mysql we're building against can be simplified a lot due to the `_ReturnAddress` intrinsic available since MSVC 2015.
* Don't include the offset we want to extract in the signature
