BugLink: http://bugs.launchpad.net/bugs/1253155

Adding a GNU debug link to a module ELF destroys the
module signature, so re-sign the module file after the objcopy.

objcopy --add-gnu-debuglink=$(dbgpkgdir)/usr/lib/debug/$$module $(pkgdir)/$$module;
scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODSECKEY) $(MODPUBKEY) $(pkgdir)/$$module;
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>