Fix multiple bugs in astreamer pipeline code.

Fix multiple bugs in astreamer pipeline code.

astreamer_tar_parser_content() sent the wrong data pointer when
forwarding MEMBER_TRAILER padding to the next streamer.  After
astreamer_buffer_until() buffers the padding bytes, the 'data'
pointer has been advanced past them, but the code passed 'data'
instead of bbs_buffer.data.  This caused the downstream consumer
to receive bytes from after the padding rather than the padding
itself, and could read past the end of the input buffer.

astreamer_gzip_decompressor_content() only checked for
Z_STREAM_ERROR from inflate(), silently ignoring Z_DATA_ERROR
(corrupted data) and Z_MEM_ERROR (out of memory).  Fix by
treating any return other than Z_OK, Z_STREAM_END, and
Z_BUF_ERROR as fatal.

astreamer_gzip_decompressor_free() missed calling inflateEnd() to
release zlib's internal decompression state.

astreamer_tar_parser_free() neglected to pfree() the streamer
struct itself, leaking it.

astreamer_extractor_content() did not check the return value of
fclose() when closing an extracted file.  A deferred write error
(e.g., disk full on buffered I/O) would be silently lost.

Discussion: https://postgr.es/m/results/98c6b630-acbb-44a7-97fa-1692ce2b827c@dunslane.net

Reviewed-By: Tom Lane <tgl@sss.pgh.pa.us>
Backpatch-through: 15