Require exact match of alternates content

The content of the alternates file (used for reference repositories)
is required to have a precise format on Windows (forward slash
separator and no trailing end of line character).  This test asserts
the alternates file contents are exactly as required, without any
trimming of leading or trailing whitespace.
Merge pull request #1 from MarkEWaite/fix_alternates_windows_test

Require exact match of alternates content