Use submodules again.

They were removed because they were causing the Travis build issues.
However, this caused massive diffs, and general git repo headaches when
switching between upstream and riscv forks.

Now that we're using github actions, it's easy to restart an action in
case there is a temporary build failure.

Change-Id: I310bc62d4a0dea0411712b9dadd8ab54c6712add
Signed-off-by: Tim Newsome <tim@sifive.com>

1 files changed, 0 insertions, 0 deletions

diff --git a/tools/git2cl b/tools/git2cl
new file mode 160000
+Subproject 8373c9f74993e218a08819cbcdbab3f3564bbeb