We somehow lost the usage_ counter increment in VulkanDescSetPool, fix that

[hrydgard]

This caused assorted problems depending on the driver, but always including spamming of resets once there's more than 512 descriptors.

Also remove a unused decimation counter.

[master1274]

Shield Tablet 32GB/LTE, Tegra K-1, Android 7.0, ARMv7, 320 dpi(1920х1200), OpenGL ES 3.2, Vulkan 1.0, Core 4x ARM Cortex-A15 - 2218 MHz.
I didn't understand if there should have been a fix v1.16.5-168-gef35cbbed fix the job Vulkan, which appeared in v1.16.5-153-g43cdb88ac, but it still doesn’t work on my device, it closes with an error. Only works GL. On the latest build v1.16.5-178-g35fcec1e4 the same

[hrydgard]

Hm, thanks for reporting that it's still broken. I have a similar device that I'll try to test on soon.

[hrydgard]

Alright, fix underway.

[hrydgard]

Turns out it was never there, so VulkanDescSetPool has been working suboptimally for some time:

1010d7a#diff-d5891ac45357a62cd705896d2ed1d0e65f635e49040cc6803c519cd5543d6a3cR152

[unknownbrackets]

Oops. And I made sure to set it to zero in so many places...

-[Unknown]