Implment "platform process list" for Windows.

Implment "platform process list" for Windows.

This patch implements basic functionality of the "platform process
list" command for Windows.  Currently this has the following
limitations.

* Certain types of filtering are not enabled (e.g. filtering by
  architecture with -a), although most filters work.
* The username of the process is not yet obtained.
* Using -v to list verbose information generates an error.
* The architecture column displays the entire triple, leading to
  misaligned formatting of the printed table.

Reviewed by: Greg Clayton
Differential Revision: http://reviews.llvm.org/D4413

llvm-svn: 212510