hygiene, extradite memory buffer into mb_*() routines
minor, actually flush the membuf to disk
chore, reserve only RLIMIT_AS / 4 before resorting to the disk
minor, flush lines that exceed the memory barrier and read them back in from a temp file
hygiene, immediately munmap() buffer upon ENOMEM
minor, only munmap() and unlink a buffer that isn't MAP_FAILED
cosmetics, put ifdef'd brace on line after conditional block, lest ...

we confuse indenters.
hygiene, actually reuse the old mapping when resizing fails

Use the buf specs of the old mapping for max.
minor, if flushing or resizing fails exit quickly from line reader
minor, similar to the read descriptor for mb_load() provide a write descriptor for mb_flsh()
minor, also fsync() upon mb_flsh()
minor, factor out temp file name generation into mb_tmpnam()
minor, upon free_mb() also set file descriptors to -1 (makes free_mb() idempotent
minor, actually fsync() upon mb_load()
minor, unlink the temporary file right away
minor, do away with fsync()ing between read and write descriptor, at least until it's reportedly broken
Merge branch 'feat/read-fifos'

* feat/read-fifos:
  minor, do away with fsync()ing between read and write descriptor, at least until it's reportedly broken
  minor, unlink the temporary file right away
  minor, actually fsync() upon mb_load()
  minor, upon free_mb() also set file descriptors to -1 (makes free_mb() idempotent
  minor, factor out temp file name generation into mb_tmpnam()
  minor, also fsync() upon mb_flsh()
  minor, similar to the read descriptor for mb_load() provide a write descriptor for mb_flsh()
  minor, if flushing or resizing fails exit quickly from line reader
  hygiene, actually reuse the old mapping when resizing fails
  cosmetics, put ifdef'd brace on line after conditional block, lest ...
  minor, only munmap() and unlink a buffer that isn't MAP_FAILED
  hygiene, immediately munmap() buffer upon ENOMEM
  minor, flush lines that exceed the memory barrier and read them back in from a temp file
  chore, reserve only RLIMIT_AS / 4 before resorting to the disk
  minor, actually flush the membuf to disk
  hygiene, extradite memory buffer into mb_*() routines