StorageBuffer::Num shold match SG_MAX_SHADERSTAGE_STORAGE_BUFFERS

[jdah]

This bit me today while doing some experiments with the new storage buffer support :D

StorageBuffer::Num == 4 while SG_MAX_SHADERSTAGE_STORAGE_BUFFERS == 8, causing the sg_shader_desc to not mark storage buffers 4..8 as used (and sokol_gfx.h to give a validation error) even when they compile just fine and are enumerated by the *_storagebuffer_slot reflection function. oops!

[floooh]

Oops good catch, sorry that was an oversight on my side. At first I had restricted the number of storage buffers to 4 per stage in sokol_gfx.h, but then bumped that number to 8 (since that's the 'minspec' in WebGPU and also in OpenGL the total number of storage buffers seems to be 16 across all shader stages).

I'll merge the PR and then kick off a CI pipeline which will update the binaries in sokol-tools-bin.

[floooh]

...link to CI pipeline: https://github.com/floooh/sokol-tools/actions/runs/9130637428

When this goes green the binaries in sokol-tools-bin will be uptodate.

Thanks for the PR!