llvm-strings: introduce basic strings tool

llvm-strings: introduce basic strings tool

This is a replacement to binutils' string tool.  It prints strings found in a
binary (object file, executable, or archive library).  It is rather bare and
not functionally equivalent, however, it lays the groundwork necessary for the
strings tool, enabling iterative development of features to reach feature
parity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286556 91177308-0d34-0410-b5e6-96231b3b80d8