Revert commitid KcCtsA53F9UQzc0t:

Revert commitid KcCtsA53F9UQzc0t:
"Make exit(), fclose(), fflush(), and freopen() comply with POSIX-2008
 requirements for setting the underlying file position when flushing
 read-mode streams, and make an fseek()-after-fflush() not change the
 underlying file position."

Something isn't correct about it and it breaks at least initdb from
the postgresql-server package.

discussed with tb@, semarie@, and deraadt@