Vulkan CTS 1.0.2.5 New tests: * Add tests for VK_KHR_relaxed_block_layouts Fixes: * Select correct memory heap index for memory import * Fix layout transition in blitting tests * Add metadata bindings in sparse tests * Fix incorrect scale in pipeline_barrier tests * copies_and_blitting: fix ambiguous signed normalized 1.0 value * Relax threshold in cube map filtering tests * cross_instance sync: run without VK_KHR_get_memory_requirements2 * Refactor synchronization test code to avoid compiler warning * Fix gcc 5.4 warnings * Add option to skip fetch external sources * Reduce the max number of concurrent pipeline cache objects