Add long form option for -g

[dhwaneetbhatt]

-g option was missing the long-form option equivalent. This PR adds the --globoff counterpart.

Documentation for this option:

-g, --globoff
This option switches off the "URL globbing parser". When you set this option, you can specify URLs that contain the letters {}[] without having curl itself interpret them. Note that these letters are not normal legal URL contents but they should be encoded according to the URI standard.