//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/1272496Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>