t5562-http-backend-content-length.sh test failures

[me-and]

As part of testing v2.35.1-2, I've found intermittent failures in t5562. It looks like it's specifically tests 13 and 14 ("push gzipped truncated" and "push gzipped empty") that are having trouble. I've also compiled v2.28.0, and I'm seeing the same failure, so I suspect this is a recent change in the Cygwin environment rather than something to do with Git.

[me-and]

Okay, this looks like it's only affecting 64-bit builds, but also like t5562.1 is failing at least some of the time, and that's setting up some of the test suite, so for now I'm gonna block the entire test out for 64-bit builds.