7175255: symlinks are wrong, which caused jdk8-promote-2 to fail (client/64/64 directories in debuginfo zips)
Summary: Fix bad paths in client/64 and server/64 debug info and symlink creation
Reviewed-by: ohair, dholmes

Summary: Work around 'gobjcopy --add-gnu-debuglink' failure by adding a temporary tool that adds the '.gnu_debuglink' section and nothing more.
Reviewed-by: sspitsyn, acorn