[llvm] r263971 - [llvm-objdump] Printing relocations in executable and shared object files. This partially reverts r215844 by removing test objdump-reloc-shared.test which stated GNU objdump doesn't print relocations, it does.

While trying to fix a bug where llvm-objdump isn't printing relocations retained with ld -emit-relocs in shared object or executables, it seems like there isn't a way to split printing dynamic relocations from non-dynamic relocations as with GNU objdump -r and -R.

I was thinking of adding a function RelocationRef::isDynamic() and filtering them this way when printing.

Since RelocationRef covers ELF/COFF/MachO we would need reasonable behaviors for each platform.

Does this seem like a good approach and does anyone have input on how this function should behave on COFF/MachO?