[llvm-objcopy] Implement --redefine-sym option

This diff implements --redefine-sym option 
for changing the name of a symbol.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D46029



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330973 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed