[arch-general] Vulkan packages

[Eric Engeström]

Hi all,

With the release of Vulkan imminent, I thought I'd prepare some packages
for Arch so that I can push them the minute it gets released :)

I was thinking of splitting it into 4 packages:
- `vulkan-loader` with everything you need to run an app compiled against
Vulkan (/usr/lib/libvulkan.so*). This is what Vulkan-apps packages would
`depend` on.
- `vulkan-headers` with everything you need to build an app for Vulkan
(/usr/include/vulkan/* & /usr/lib/pkgconfig/vulkan.pc) (depends on
`-loader`)
- `vulkan-sdk` with all the debugging and validation stuff from LunarG
(/usr/bin/*, /usr/share/vulkan/*) (depends on `-headers` + `-loader`)
- `vulkan-manpages` (self-explanatory :P)
I've also made `-git` versions of all of those, except the `-sdk`: I can't
make it clean enough for a PKGBUILD without heavy patching of upstream's
build scripts (I'm hoping somebody fixes that soon enough, I don't have the
patience to do it myself :P).

Does this sound reasonable?

Since those are all interconnected, should I make a single split package
(like `mesa`), or separate packages? I've written them as separate packages
for now, but they're all in `groups=('vulkan')`

Note that Intel's open-source ICD is being merged into Mesa, and the CTS is
merged into AOSP's dEQP, so there's no need to make new packages for them.

I'm also ready to take on the responsibility of maintaining those packages.
Should be implicit, but I thought I'd mention it, especially if they get
moved to `community` :)

Cheers,
Eric Engeström