[Libguestfs] [PATCH v8] v2v: Add -o rhv-upload output mode (RHBZ#1557273).

v7 was here: https://www.redhat.com/archives/libguestfs/2018-March/msg00143.html Since then: - Earlier patches are now upstream. - The to-do list is moved from the commit message to the TODO file. - This version forces -of raw + -oa sparse and gives an error in any other mode. We intend to lift these restrictions later. - Tested against latest imageio which supports longer timeouts, zero, flush (but not trim), Rich.