Merge branch 'amd-immutable-sampler-fix' into 'master'

Fix to always allocate storage in descriptor pools for samplers

Fix to always allocate storage in descriptor pools for samplers, indifferent of whether they are immutable or not.

Fixes #37

See merge request !273

diff --cc external/vulkancts/modules/vulkan/binding_model/vktBindingShaderAccessTests.cpp
Simple merge