The io/ioutil package has been deprecated in Go 1.16. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
It was only used for two consts, which are unlikely to change, but the
"opts" package currently also imports libnetwork/ipamutils, which has
an `init()` function that does some heavy lifting, and not needed for
this utility's purpose.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>