libopenmpt not found unless in love2d project root (windows)

Hi! I've been trying to include this into a project, and after a bit of poking around got it working on windows.

unfortunately, it only seems to work if I put openmpt.lua and all the openmpt libraries into the root directory of the love2D project. if I try to put any of it in a subdirectory, I get this error:

`cannot load module 'libopenmpt': The specified module could not be found.`

resulting from this line:

`local openmpt = ffi.load("libopenmpt.dll")`

regardless of specifying the relative path.

anything I could be doing wrong? again, it works fine if I just dump all the files into the project root.

Start with openmpt.lua at the ffi.load("libopenmpt.dll") call and reproduce the Windows behavior with the files in the project root versus a subdirectory. Check what path handling is involved, and consider the issue done when libopenmpt and its related libraries load successfully from the intended subdirectory in a LÖVE project.

Written by the indexing model from the issue text.