Given that we can now handle the target's disk shorthand, in addition
to an absolute path to the file or block device used on the host,
the term 'disk' fits a bit better as the parameter name than 'path'.

* include/libvirt/libvirt.h.in: Update some parameter names.
* src/libvirt.c (virDomainBlockStats, virDomainBlockStatsFlags)
(virDomainBlockPeek, virDomainGetBlockInfo, virDomainBlockJobAbort)
(virDomainGetBlockJobInfo, virDomainBlockJobSetSpeed)
(virDomainBlockPull): Likewise.