Don't use chunking for stream writes

We're currently splitting up large writes into 8K size chunks, which
adversely affects I/O performance in some cases. Splitting up writes
doesn't

Don't use chunking for stream writes

We're currently splitting up large writes into 8K size chunks, which
adversely affects I/O performance in some cases. Splitting up writes
doesn't make a lot of sense, as we already must have a backing buffer,
so there is no memory/performance tradeoff to be made here.

This change disables the write chunking at the stream layer, but
retains the current retry loop for partial writes. In particular
network writes will typically only write part of the data for large
writes, so we need to keep the retry loop to preserve backwards
compatibility.

If issues due to this change turn up, chunking should be reintroduced
at lower levels where it is needed to avoid issues for specific streams,
rather than unnecessarily enforcing it for all streams.

show more ...

Trim trailing whitespace in tests

test to stream function set_file_buffer.phpt();