configure on FreeBSD reports "grep: The -P option is not supported"

[Rebecca Cran <rebecca@xxxxxxxxx>]

It looks like commit 7ff204c83595cd7d6b7b6a813d9fda97afd25198 introduced an error on some systems such as FreeBSD, whose grep doesn't support -P.

num() {
  echo "$1" | grep -P -q "^[0-9]+$"
}

./configure now reports:

grep: The -P option is not supported
seed_buckets                  4

Is -P required?

--
Rebecca Cran