Bug 1451104 - part 6 - don't remove the libstdc++ files from the mingw build; r=glandium

History does not disclose why we needed this, but in the brave new GCC
6-compiled world, deleting these files means that host links can no
longer find libstdc++, which causes problems.  Let's put the files back.

Differential Revision: https://phabricator.services.mozilla.com/D22884

--HG--
extra : moz-landing-system : lando

taskcluster/scripts/misc/build-clang-trunk-mingw.sh

@@ -321,7 +321,6 @@ popd
 mkdir -p $UPLOAD_DIR
 
 pushd $(dirname $INSTALL_DIR)
-rm -f clang/lib/libstdc++*
 tar caf clangmingw.tar.xz clang
 mv clangmingw.tar.xz $UPLOAD_DIR
 popd