tools/libs: Fix stable library ABI breakage from c/s e1ed22be85

tools/libs: Fix stable library ABI breakage from c/s e1ed22be85

For libxengnttab.map, introducing a new VERS* section must be matched with a
equivalent SONAME bump.

For libxencall.map, the hunk as presented would have been ok, if Xen 4.11
hadn't been released between xencall_buffers_never_fault() and xencall_fd()
being introduced.  Given the timing of the release, xencall_fd() needs moving
into a new VERS_1.2 section.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <Ian.Jackson@eu.citrix.com>