spirv: fix up calling conventions for vulkan

* Fragment and Vertex CCs are only valid for SPIR-V when
  running under Vulkan.
* Emit GLCompute instead of Kernel for SPIR-V kernels.
6de456c179Robin Voetter committed on 10/27/2024, 2:19:55 PMparent9b42bc1
3 files changedLine totals unavailable