[llvm-readelf] Make llvm-readelf more compatible with GNU readelf.

[llvm-readelf] Make llvm-readelf more compatible with GNU readelf.

Summary:
This change adds a bunch of options that GNU readelf supports. There is one breaking change when invoked as `llvm-readobj`, and three breaking changes when invoked as `llvm-readelf`:
 - Add --all (implies --file-header, --program-headers, etc.)
 - [Breaking] -a is --all instead of --arm-attributes
 - Add --file-header as an alias for --file-headers
 - Replace --sections with --sections-headers, keeping --sections as an alias for it
 - Add --relocs as an alias for --relocations
 - Add --dynamic as an alias for --dynamic-table
 - Add --segments as an alias for --program-headers
 - Add --section-groups as an alias for --elf-section-groups
 - Add --dyn-syms as an alias for --dyn-symbols
 - Add --syms as an alias for --symbols
 - Add --histogram as an alias for --elf-hash-histogram
 - [Breaking] When invoked as `llvm-readelf`, -s is --symbols instead of --sections
 - [Breaking] When invoked as `llvm-readelf`, -t is no longer an alias for --symbols

Reviewers: MaskRay, phosek, mcgrathr, jhenderson

Reviewed By: MaskRay, jhenderson

Subscribers: sbc100, aheejin, edd, jhenderson, silvas, echristo, compnerd, kristina, javed.absar, kristof.beyls, llvm-commits, Bigcheese

Differential Revision: https://reviews.llvm.org/D54124

llvm-svn: 346685