add debuginfo support

This commit adds basic debuginfo support.  It is "basic" in as much as
it does not try to parse the DWARF data to figure out which parts
pertain to the changed code.  It simply includes all .debug_ and
.rela.debug_ section and strips out any rela entries that reference
unchanged symbols.  This corrupts the debuginfo for unchanged symbols
but since they are not going to be included anyway, there should be no
way to reference that information.

Signed-off-by: Seth Jennings <sjenning@redhat.com>