Add -expand-relocs to llvm-readobj

This option expands shown relocations from single line to a dictionary
format:

  Relocation {
    Offset: 0x4
    Type: R_386_32 (1)
    Symbol: sym
    Info: 0x0
  }

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179359 91177308-0d34-0410-b5e6-96231b3b80d8
Add extensive relocation tests for llvm-readobj

This test ensures that relocation type names returned by libObject match
the raw relocation type value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179360 91177308-0d34-0410-b5e6-96231b3b80d8