[tools] Add 'signed off by' tag to scripts

As the communty will change from CLA to DCO we need to add
'Signed off by' tags to commit messages, which can be done
by a '-s' switch in 'git commit' commands.

Change-Id: I6536babdb91440eb938da36065e8161708dfcbf6

tools/bulk_review.sh

@@ -99,7 +99,7 @@ for team in "${!files_by_team_release[@]}" ; do
     git checkout -b $branch_name -t origin/master
 
     git add ${files_by_team_release[$team]}
-    git commit \
+    git commit -s\
         -m "[$team] $subject" \
         -m "$body"
 

tools/functions

@@ -75,7 +75,7 @@ function update_gitreview {
 defaultbranch=$branch"
     echo "$grcontents" > .gitreview
     git add .gitreview
-    git commit -m "Update .gitreview for $branch"
+    git commit -s -m "Update .gitreview for $branch"
     git show
     local shortbranch=$(basename $branch)
     git review -t "create-${shortbranch}"
@@ -93,7 +93,7 @@ function update_upper_constraints {
     sed -i~ -e "s,-c.*{\(env:UPPER_CONSTRAINTS_FILE\)[^ ]*},-c{\1:$uc_url}," tox.ini
     if ! git diff --exit-code >/dev/null 2>&1 ; then
         git add tox.ini
-        git commit -m "Update UPPER_CONSTRAINTS_FILE for $branch"
+        git commit -s -m "Update UPPER_CONSTRAINTS_FILE for $branch"
         git show
         local shortbranch=$(basename $branch)
         git review -t "create-${shortbranch}"