llvm: add llvm-dlltool support to the archiver

A PE COFF spec compliant import library generator.
Intended to be used with mingw-w64.

Supports:
PE COFF spec (section 8, Import Library Format)
PE COFF spec (Aux Format 3: Weak Externals)

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D29892

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308329 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed