Fix build of tests/*

"make -C tests" should now build successfully.

Signed-off-by: John Else <john.else@citrix.com>
Add bindings for xc_[gntshr|gnttab]_[open|close] and helper functions.

Signed-off-by: John Else <john.else@citrix.com>
Makefile changes.

Signed-off-by: John Else <john.else@citrix.com>
Add binding to xc_gntshr_share_pages.

Signed-off-by: John Else <john.else@citrix.com>