vcpu: improve vcpu support in xen command line

vcpu: improve vcpu support in xen command line

This patch series focuses on xendConfigVersion 2 (xm_internal) and 3
(xend_internal), but leaves out changes for xenapi drivers.

See this link for more details about vcpu_avail for xm usage.
http://lists.xensource.com/archives/html/xen-devel/2009-11/msg01061.html

This relies on the fact that def->maxvcpus can be at most 32 with xen.

* src/xen/xend_internal.c (xenDaemonParseSxpr)
(sexpr_to_xend_domain_info, xenDaemonFormatSxpr): Use vcpu_avail
when current vcpus is less than maximum.
* src/xen/xm_internal.c (xenXMDomainConfigParse)
(xenXMDomainConfigFormat): Likewise.
* tests/xml2sexprdata/xml2sexpr-pv-vcpus.sexpr: New file.
* tests/sexpr2xmldata/sexpr2xml-pv-vcpus.sexpr: Likewise.
* tests/sexpr2xmldata/sexpr2xml-pv-vcpus.xml: Likewise.
* tests/xmconfigdata/test-paravirt-vcpu.cfg: Likewise.
* tests/xmconfigdata/test-paravirt-vcpu.xml: Likewise.
* tests/xml2sexprtest.c (mymain): New test.
* tests/sexpr2xmltest.c (mymain): Likewise.
* tests/xmconfigtest.c (mymain): Likewise.