[Libguestfs] [PATCH] Introduce a wrapper around xmlParseURI.

[Richard W.M. Jones]

An alternate solution to:

  https://www.redhat.com/archives/libguestfs/2017-December/msg00035.html
  "[PATCH] v2v: -i vmx: Allow ssh URLs to use spaces."

is to classify all URLs processed by libguestfs as either ordinary
URLs or the special non-standard URLs that we use for things like
‘virt-v2v -i vmx’ and ‘guestfish --add’.

For the non-standard URLs, provide a wrapper around xmlParseURI which
turns spaces into %20, and other things.

This patch reveals that there are bugs in the qemu ssh driver (or
libssh2).  It cannot handle spaces in the file path or in fact any
non-ASCII character.

Rich.