Bug 1277338 - Part 11: Add js/rust to standalone JS source packages; r=sfink

This commit ensures that we copy the js/rust crate into the resulting source
tarball whenever we make standalone JS releases.

js/src/make-source-package.sh

@@ -110,6 +110,7 @@ case $cmd in
     cp -pPR ${TOPSRCDIR}/mfbt ${tgtpath}
     cp -p ${SRCDIR}/../moz.configure ${tgtpath}/js
     cp -pPR ${SRCDIR}/../public ${tgtpath}/js
+    cp -pPR ${SRCDIR}/../rust ${tgtpath}/js
     cp -pPR ${SRCDIR}/../examples ${tgtpath}/js
     find ${SRCDIR} -mindepth 1 -maxdepth 1 -not -path ${STAGING} -a -not -name ${pkg} \
         -exec cp -pPR {} ${tgtpath}/js/src \;