Currently implementation of rand/random built-in functions
use rand_r of C library. We recognized its randomness was poor.
pcg32 of third party library shows better randomness than rand_r.
Testing:
Revise unit test in expr-test
Add E2E test to random.test
Change-Id: Idafdd5fe7502ff242c76a91a815c565146108684
Reviewed-on: http://gerrit.cloudera.org:8080/8355
Reviewed-by: Jim Apple <jbapple-impala@apache.org>
Tested-by: Impala Public Jenkins
