Fix #76859 stream_get_line skips data if used with data-generating filter

Fix #76859 stream_get_line skips data if used with data-generating filter

stream_get-line repeatedly calls php_stream_fill_read_buffer until
enough data is accumulated in buffer. However, when stream contains
filters attached to it, then each call to fill buffer essentially
resets buffer read/write pointers and new data is written over old.
This causes stream_get_line to skip parts of data from stream
This patch fixes such behavior, so fill buffer call will append.