Perform wildcard expansion in Process::GetArgumentVector on Windows (PR17098)

Perform wildcard expansion in Process::GetArgumentVector on Windows (PR17098)

On Windows, wildcard expansion isn't performed by the shell, but left to the
program itself. The common way to do this is to link with setargv.obj, which
performs the expansion on argc/argv before main is entered. However, we don't
use argv in Clang on Windows, but instead call GetCommandLineW so we can handle
unicode arguments. This means we have to do wildcard expansion ourselves.

A test case will be added on the Clang side.

Differential Revision: http://reviews.llvm.org/D4529

llvm-svn: 213114