The xfstest does not support _supported_os

Reference: 
https://github.com/kdave/xfstests/commit/a860a167d87a75a4ed96c9b371c48f0f21729191

Please remove "_supported_os Linux" from:
/code/tests/ace-base/base_xfstest.sh and
/code/tests/ace-base/base_xfstest_concise.sh

