Previously, this was broken - by setting PointerToSymbolTable to zero
but still actually writing the string table length, the object file
header was corrupted.

Differential Revision: https://reviews.llvm.org/D56584

llvm-svn: 350926

This is an initial implementation of no-op passthrough copying of COFF
with objcopy.

Differential Revision: https://reviews.llvm.org/D54939

llvm-svn: 349605