Regress tests for negative offsets, wrapping offsets, and the lack of
interaction of pwrite/pwritev with O_APPEND.

Based on a patch from Alexander Polakov (polachok at gmail.com)
Further tests with

Regress tests for negative offsets, wrapping offsets, and the lack of
interaction of pwrite/pwritev with O_APPEND.

Based on a patch from Alexander Polakov (polachok at gmail.com)
Further tests with deraadt@

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Verify this fails with ESPIPE on ttys

add missing includes
ok deraadt@ tedu@ dhartmei@ krw@

various cleanups; david says results are same

test pwritev