objdump -S/--disassemble should add -r/--reloc flag

I was comparing the output of Clang -fPIC and -fPIE with Diffoscope, generating https://people.freebsd.org/~emaste/pic-pie/clang.html. Via Twitter Rich Felker commented that the objdump disassembly (i.e., objdump --line-numbers --disassemble --demangle --section=.text {}) should include relocations as well and indeed this would make the comparison much more useful in this instance.

https://twitter.com/RichFelker/status/1095084000916500483

I'll attach a patch tomorrow.