[llvm-objcopy] Add support for static libraries

This diff adds support for handling static libraries 
to llvm-objcopy and llvm-strip.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D48413


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336455 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed