[llvm-strings] Add support for the -a/--all options

They don't actually change nay behaviour, as llvm-strings currently
checks the whole object without looking at individual sections anyway.

This allows using llvm-strings in a context that explicitly passes
the -a option.

Differential Revision: https://reviews.llvm.org/D40020

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318185 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed