As pointed out in https://bugzilla.redhat.com/show_bug.cgi?id=807053
relocating a compressed section will corrupt it. To more properly
support compressed sections we should finish the roland/relocate branch
for lazy relocations work. The best we can do for now is to not corrupt
the contents of the compressed sections and not crash when we don't have
all Dwarf debug section data. The attached two patches do that.