Link with exchndl, instead of dynamically loading it.

It caused problems with crash reports not being made if the current working directory gets changed. Not even recommended anymore per the drmingw readme https://github.com/jrfonseca/drmingw#exchndl

This do mean that both exchndl.dll and mgwhelp.dll are now required for the game to run, but not like there's a reason to not include both.