MFC r268926, r268930, r268983:

MFC	r268926, r268930, r268983:

Use a correct errno in freopen.
Use EBADF instead of EINVAL when working around incorrect O_ACCMODE.

Adjust errno on failed prepwrite.

rewind: always clear error indicator as required by POSIX.

Obtained from:	Apple Inc. (Libc 997.90.3)
Phabric:	D442

git-svn-id: svn://svn.freebsd.org/base/stable/10@269482 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f