Linux build issues

[ChristophHaag]

I'll just put everything in one issue instead of making multiple across all the related repositories.

pd-hs:

Two ifdefs need a linux branch (_WIN32 is okay for now)
https://github.com/lukexi/pd-hs/blob/3a17e75cb7a5d20814d4c38e2b98a53e0acc012e/cbits/libpd_openal.c#L1
https://github.com/lukexi/pd-hs/blob/3a17e75cb7a5d20814d4c38e2b98a53e0acc012e/cbits/libpd_openal.c#L172

openvr-hs:

This whole file:
https://github.com/lukexi/openvr-hs/blob/ebbeb8c5393e7bbe8aaa46642fce9776c3af0265/cbits/openvr_mingw.h
OpenVR headers are actually broken upstream. Here are two pull requests that I think are enough to make openvr_capi.h work.
ValveSoftware/openvr#58
ValveSoftware/openvr#278
Not sure how to best do this, but I kinda "maintain" it on https://github.com/ChristophHaag/openvr/blob/master/headers/openvr_capi.h
I haven't checked how much different the mingw version is, maybe needs some merging.

vr-pal:

Windows only libs:
https://github.com/lukexi/vr-pal/blob/c84ecd001e2af4fb73c27d76ffb0b8a4cfd51e47/vr-pal.cabal#L44
https://github.com/lukexi/vr-pal/blob/c84ecd001e2af4fb73c27d76ffb0b8a4cfd51e47/vr-pal.cabal#L89
Windows only code:
https://github.com/lukexi/vr-pal/blob/c84ecd001e2af4fb73c27d76ffb0b8a4cfd51e47/cbits/win32_SetProcessDpiAware.c

This last issue is where I have stopped for now, because it needs some more involved work to remove it from the project. At least that's what I think.

[lukexi]

Thanks so much Christoph! Will get to these asap!

[slowriot]

PR 58 finally got accepted after only 9 months, so we're making some progress ;)

[ChristophHaag]

Yea, the stdbool.h one too. To be fair, reviewing such complex pull requests can take a long time!

On a more serious notes, it probably has something to do with Valve demonstrating SteamVR on Linux recently. Looks like things are slowly but surely starting to move.

[slowriot]

Let's hope so!

[lukexi]

I just finished getting Rumpus back up and running on OS X so Linux shouldn't be too far away now! I need to set up a dev machine/VirtualBox first...