libgfapi: Support a way to indicate thin client mount

[poornimag]

Issue #242 implements gfproxyd and thin client. With this, gfapi requires two things:

1. Modify api to specify usage of thin client vol file.
2. If thin is specified, the memory and thread management in libgfapi should reduce the resource consumption.

[pranithk]

@poornimag hey, I am looking to leverage this for collecting statfs information even when the number of volumes is in thousands. Do you have any agenda/plan about when to complete this? What will be the estimated size of the gfapi client when this work completes. Do you have any idea about this?

[stale]

Thank you for your contributions.
Noticed that this issue is not having any activity in last ~6 months! We are marking this issue as stale because it has not had recent activity.
It will be closed in 2 weeks if no one responds with a comment here.

[stale]

Closing this issue as there was no update since my last update on issue. If this is an issue which is still valid, feel free to open it.