In certain case, it could take more than just 0/1, but 2 bits should
be enough.

as it's a flag now, just set the value

32 bytes are spared on 64-bit build

Sometimes int is overflown. That might still come out with a right
result, but is ofc not clean.

As revealed by #72857, this value conflicts with the xport option.
Wrong code can otherwise cause streams misbehave, fe if local and
network streams APIs are mixed.

These are either in debug code (fix them), commented out (drop
them) or in dead compatibility macros (drop them).

One usage was in php_stream_get_from_zval(), which we have not used
since at least PHP 5.2 and, judging from the fact that nobody
complained about it causing compile errors in PHP 7, nobody else
uses it either, so drop it.

There are still remaining uses in mysqli embedded and odbc birdstep.
These probably need to be dropped outright.