[llvm-objdump] support '--syms' as an alias of -t

This adds support for '--syms' as an alias of '-t' for llvm-objdump,
fixing PR39406 (https://bugs.llvm.org/show_bug.cgi?id=39406).

Patch by Higuoxing (Xing).

Differential Revision: https://reviews.llvm.org/D53803

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345697 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed