Correct count in sim_fwrite

[LegalizeAdulthood]

Fixes #539

[markpizz]

@LegalizeAdulthood , Since you've never actually had commits merged to the simh repo, you might not have realized that there is a convention in the simh repo which was established based on the great suggestion of Timothe Litt (@tlhackque) some 13 years ago. Specifically, the commit comments should be of the form:

AFFECTED-FACILITY: One line description max 80 characters
<blank-line-if-additional-comments>
Optional additional comments as needed for as many lines as would be useful < 80 characters

AFFECTED-FACILITY would be things like FIO (in this case), SCP, ETHER, TMXR etc., or (one or more simulator names).

Also, the additional comments are best when they include the description and justification for the change since that info gets carried anywhere the repo goes, while pointers to PR comments or Issue comments are stuck on github.

So, the commit for this PR should look at least like:

FIO: Fix Big Endian sim_fwrite() error

maybe with a summary of what was discussed in the Issue message.

Additionally, although you are the one committing the change in your repo, if I were doing this, I would specifically set Perry Metzger <perry@piermont.com> as the Author.

[LegalizeAdulthood]

Go away