Fix various sign-compare warnings due to write return value

Fix various sign-compare warnings due to write return value

write takes size_t as count (unsigned int on
Windows) and returns ssize_t (int on Windows).
But we often want to compare the return value
to the count.

Generally we can just rely on the fact that
sizeof(ssize_t) == sizeof(size_t) and use that
for all values. (Until we want to introduce
-Wsign-conversion that is...)

Change-Id: I3eb4581980f532cb2960b37a6fa43a7baee4b603
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1513
Message-Id: <20260306163337.2756-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg35963.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>