Fixes issue #290 - set is_parent_rta for ParseDescriptorBlockVariableSizes

[danginsburg]

so that they don't get padded to 16-byte size.

Changes the output for the shader in the bug report as follows:

generator       : Khronos SPIR-V Tools Assembler
source lang     : Unknown
source lang ver : 1
source file     :
entry point     : main (stage=CS)
local size      : (1, 1, 1)


  Push constant blocks: 1

    0:
      spirv id : 2
      name     : pushConstant (Data_std430)
          // size = 4, padded size = 4
          struct Data_std430 {
              int x; // abs offset = 0, rel offset = 0, size = 4, padded size = 4
          } pushConstant;



  Descriptor bindings: 1

    Binding 0.0
      spirv id : 3
      set      : 0
      binding  : 0
      type     : VK_DESCRIPTOR_TYPE_STORAGE_IMAGE (UAV)
      count    : 1
      accessed : true
      name     : g_Output

[spencer-lunarg]

This will need to update the golden test YAML for other things

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
python tests\build_golden_yaml.py

The case you had this works, but I am still looking into if the BufferDeviceAddress handles make sense or not for the new size