Vulkan:maxPerStageDescriptorStorageBuffers = 16
Vulkan:maxPerStageDescriptorStorageBuffers = 16

Update the maxPerStageDescriptorStorageBuffers from 4 to 16.
ANGLE requires at least 12 for GLES3.1 support, and 16 is a common
number among actual hardware so bumping to 16.

Bug: swiftshader:136
Change-Id: I2790a8cab197c773aa14d9c1b0fdcc5ca8356b25
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38068
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Tested-by: Tobin Ehlis <c15ba1c6ec8841cd136fafb26b333b1f76c86fb4@google.com>

bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,google/swiftshader