Fix vulkan_null perftests on Linux //build/config/gcc:rpath_for_built_shared_libraries was supposed to be used to add . to rpath (which affected only release. I didn't investigate how it was affecting debug). This resulted in libVkICD_mock_icd.so not being found and vulkan_null tests being ignored. Change-Id: I71fb8578f873e4bed602b2c3dcf6d93240dcf30e Reviewed-on: https://chromium-review.googlesource.com/c/1272496 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>