Previously, did not check the return of TryLink() before appending, so unsupported flags can be used when building shared libraries. This patch adds checking. Jira Issue: https://gem5.atlassian.net/browse/GEM5-1115 Change-Id: Ief62be15009cae9e02aaaa81b4d9c2d7b26e0223 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/53025 Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Gabe Black <gabe.black@gmail.com> Maintainer: Jason Lowe-Power <power.jg@gmail.com> Maintainer: Gabe Black <gabe.black@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>