elf: make r_debug fallback discovery work for PIEs
elf: make r_debug fallback discovery work for PIEs

The base address that lives in the auxilliary vector for the main
dynamic object is completely wrong when the executable is a PIE.

Iterating through the loaded objects with dl_iterate_phdr is the
"official" way of getting to the dynamic segment.

Snaipe/Mimick,Snaipe/Mimick