libmapi: Impelement copy for struct SPropValue for multivalue properties

Signed-off-by: Kamen Mazdrashki <kmazdrashki@zentyal.com>
libmapi: Remove abort for Multivalue properties in mapi_copy_spropvalues()

I used smb_abort() for now, but it is really OC_ABORT(false)
that we should use here

Signed-off-by: Kamen Mazdrashki <kmazdrashki@zentyal.com>