We have to actually determine the proper `SIZEOF_OFF_T`.
Interestingly, it is `4` on Windows x64.

We also have to prevent the redefinition in pg_config.h.  The clean
solution would likely be to not include pg_config.h at all, but that's
out of scope for BC reasons for now.

The php_stream_read() and php_stream_write() functions now return
an ssize_t value, with negative results indicating failure. Functions
like fread() and fwrite() will return false in that case.

As a special case, EWOULDBLOCK and EAGAIN on non-blocking streams
should not be regarded as error conditions, and be reported as
successful zero-length reads/writes instead. The handling of EINTR
remains unclear and is internally inconsistent (e.g. some code-paths
will automatically retry on EINTR, while some won't).

I'm landing this now to make sure the stream wrapper ops API changes
make it into 7.4 -- however, if the user-facing changes turn out to
be problematic we have the option of clamping negative returns to
zero in php_stream_read() and php_stream_write() to restore the
old behavior in a relatively non-intrusive manner.

Symbol is not used anywhere in the code and also Postgresql 7.x is
EOL anyway.

Closes GH-4453

This reverts commit 1e265174ed8b361c2d8b9c050f9e3b1f7034acc9.

RFC: https://wiki.php.net/rfc/tostring_exceptions

And convert some object to string conversion related recoverable
fatal errors into Error exceptions.

Improve exception safety of internal code performing string
conversions.

This is our most common intermittent failure. I don't understand
why it happens and can't reproduce it, but defining an explicit
sort order seems worth a shot...

This removes the example script in favour of the manual:
https://www.php.net/manual/en/book.pgsql.php

Patch for integrating these functions as an example has been submitted
also to PHP manual via edit.php.net.