[SMT-COMP] Final benchmarks

[Clark Barrett]

The final version of the benchmarks for the competition has been posted on the
SMT-LIB website.

The changes since the last version include:

- the status and difficulty have been updated for all benchmarks
- a significant number of benchmarks have been moved from QF_AUFLIA to QF_AX
  since they only involve array operations.

Note that due to lack of interest, the UFNIA benchmarks will not be in the competition this year.

Sincerely,
The SMT-COMP organizers