[AIX]implement the --syms and using "symbol index and qualname" for --sym...

[AIX]implement the --syms and using "symbol index and qualname" for --sym --symbol--description for llvm-objdump for xcoff

Summary:

for xcoff :

implement the getSymbolFlag and getSymbolType() for option --syms.
llvm-objdump --sym , if the symbol is label, print the containing section for the symbol too.
when using llvm-objdump --sym --symbol--description, print the symbol index and qualname for symbol.
for example:
--symbol-description
00000000000000c0 l .text (csect: (idx: 2) .foov[PR]) (idx: 3) .foov

and without --symbol-description
00000000000000c0 l .text (csect: .foov) .foov

Reviewers: James Henderson,Esme Yi

Differential Revision: https://reviews.llvm.org/D109452