buildx/build
Justin Chadwell 48067735fc Update golint to revive
Resolves the following message in golangci output:

> The linter 'golint' is deprecated (since v1.41.0) due to: The
repository of the linter has been archived by the owner.  Replaced by
revive.

Additionally, fix a minor linting issue discovered by revive.

Signed-off-by: Justin Chadwell <me@jedevc.com>
..
build.go Update golint to revive
url.go Remove uses of deprecated io/ioutil
utils.go build: add ulimit support