[Chromoting] Add runtime hardened option to mac host

Change-Id: I50b6548b891a123c63b9513d469b51c0efd664b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1779402
Auto-Submit: Gary Kacmarcik <garykac@chromium.org>
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Commit-Queue: Jamie Walch <jamiewalch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692297}

remoting/host/installer/mac/do_signing.sh

@@ -127,9 +127,11 @@ sign() {
 
   echo Signing "${name}"
   if [[ -n "${keychain}" ]]; then
-    codesign -vv -s "${id}" --keychain "${keychain}" "${name}"
+    codesign -vv --sign "${id}" --options runtime \
+        --keychain "${keychain}" "${name}"
   else
-    codesign -vv -s "${id}" "${name}"
+    codesign -vv --sign "${id}" --options runtime \
+        "${name}"
   fi
   codesign -v "${name}"
 }