Test workgroup size setting combinations

Test workgroup size setting combinations

Vulkan shader validation rules include:

 For each compute shader entry point, either a LocalSize execution mode
 or an object decorated with the WorkgroupSize decoration must be
 specified.

Glslang always emits an "OpExecutionMode %main LocalSize 1 1 1".
We should be able to specify workgroup size with a spec constant
uvec3, and remove OpExecutionMode for LocalSize.

This patch tests 3 combinations:
  literal local size, no spec constant workgroup size
  literal local size, and spec constant workgroup size
  no literal local size, and spec constant workgroup size

Affects:

dEQP-VK.spirv_assembly.instruction.compute.opnop.*

VK-GL-CTS issue: 629

Compoonents: Vulkan

Change-Id: I5401cac9e569bf1ed77920015ba085b6a8f28a11