[obj2yaml][ELF] Do not print empty Link and Info fields for ELF sections.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208905 91177308-0d34-0410-b5e6-96231b3b80d8
[obj2yaml][ELF] Print relocation's offset as a hex number. Use a proper
types to hold relocation's offset and addend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208906 91177308-0d34-0410-b5e6-96231b3b80d8