COMP: Fix MD5 check on Windows by using binary mode for output

[benbennett]

Must use ios::binary because in-memory string uses LF

[lassoan]

Thank you, it looks good to me, except a small but important thing. Github discussions may be lost in the future (e.g., if the repository has to be moved to a different provider), therefore useful/important information must be saved in the source code or commit comments.

In this case, rationale for the change (explanation of the code) is only in the Github discussion. Please add a comment like // Must use ios::binary because in-memory string uses LF and CR/LF would be used on Windows in non-binary mode to the source code. It is also useful to add some high-level information about a commit (motivation, overall design, etc.). In this case, it would describe why the change was made (e.g., to fix the mechanism that makes repeated builds faster).