llvm-readobj: add support to dump COFF export tables

This enhances llvm-readobj to print out the COFF export table, similar to the
-coff-import option.  This is useful for testing in lld.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225120 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed