Revert "llvm-objdump: Dump COFF import table if -private-headers option is given."

This reverts commit r191472 because it's failing on BE machine.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191480 91177308-0d34-0410-b5e6-96231b3b80d8