Merge branch 'ps/reftable-alloc-failures'

Merge branch 'ps/reftable-alloc-failures'

The reftable library is now prepared to expect that the memory
allocation function given to it may fail to allocate and to deal
with such an error.

* ps/reftable-alloc-failures: (26 commits)
  reftable/basics: fix segfault when growing `names` array fails
  reftable/basics: ban standard allocator functions
  reftable: introduce `REFTABLE_FREE_AND_NULL()`
  reftable: fix calls to free(3P)
  reftable: handle trivial allocation failures
  reftable/tree: handle allocation failures
  reftable/pq: handle allocation failures when adding entries
  reftable/block: handle allocation failures
  reftable/blocksource: handle allocation failures
  reftable/iter: handle allocation failures when creating indexed table iter
  reftable/stack: handle allocation failures in auto compaction
  reftable/stack: handle allocation failures in `stack_compact_range()`
  reftable/stack: handle allocation failures in `reftable_new_stack()`
  reftable/stack: handle allocation failures on reload
  reftable/reader: handle allocation failures in `reader_init_iter()`
  reftable/reader: handle allocation failures for unindexed reader
  reftable/merged: handle allocation failures in `merged_table_init_iter()`
  reftable/writer: handle allocation failures in `reftable_new_writer()`
  reftable/writer: handle allocation failures in `writer_index_hash()`
  reftable/record: handle allocation failures when decoding records
  ...