Make safetyhook a shared library

[Kenzzer]

Continuation of alliedmodders/safetyhook#7

Compiling safetyhook as a static library has fattened Sourcemod releases. This PR attempts to move safetyhook into a shared library to lessen the release size, a side benefit of this is how using CDetour by 3rd party extensions will become significantly easier. (Though we would need to address if & how to distribute the .so/.lib file)