Remove unnecessary uninstall of oclint
Remove unnecessary uninstall of oclint

See https://changelog.travis-ci.com/oclint-is-removed-from-mac-builds-79270
jcupitt/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips,lovell/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips