Bump `PORT_REVISION` for the change.

get_release(..):

The function was incorrectly modifying a pointer that wasn't the original
calloc'ed pointer, tripping asserts when MALLOC_PRODUCTION wasn't enabled
in jemalloc [*].

- Use one temporary buffer (`release`) instead of two (`release` and
  `version`).
- Improve temporary memory idiom for managing memory used with
  sysctlbyname(3) by first checking the length, mallocing the buffer,
  then filling it with a second call to sysctlbyname(3).
- Use strchr(3) instead of handrolling it in a while-loop and to
  avoid the improper free(3) of the memory allocated for `release`.

main(..):

- Use asprintf instead of calloc + sprintf.
- Use constant `pasting` with `INDEX_FILE` instead of passing it in to
  asprintf(3).
- Fix error message when unable to open `INDEX_FILE`.