Return Windows error code when create-process fails.

COULD_NOT_CREATE_PROCESS makes up about 10% of the setup errors; include the actual DWORD result code returned by ::CreateProcess by placing all result information into the proper location of the Registry for reading by Omaha.

BUG=

Review URL: https://codereview.chromium.org/1247993002

Cr-Commit-Position: refs/heads/master@{#341938}
11 files changed