vendor/grep: upgrade from 2.22 to 3.4

Vendor branch: upgrade grep from 2.20 => 2.22

Upgrade grep from 2.14 => 2.20 on the vendor branch

Upgrade grep version 2.9 to 2.12 on the vendor branch

Upgrade grep version 2.7 to 2.9 on the vendor branch

Import grep-2.7