checkpatch: Add xendevicemodel_handle to the list of types

checkpatch: Add xendevicemodel_handle to the list of types

This avoids checkpatch misparsing (as statements) long function
definitions or declarations, which sometimes start with constructs
like this:

  static inline int xendevicemodel_relocate_memory(
      xendevicemodel_handle *dmod, domid_t domid, ...

The type xendevicemodel_handle does not conform to Qemu CODING_STYLE,
which would suggest CamelCase.  However, it is a type defined by the
Xen Project in xen.git.  It would be possible to introduce a typedef
to allow the qemu code to refer to it by a differently-spelled name,
but that would obfuscate more than it would clarify.

CC: Eric Blake <eblake@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Reviewed-by: Eric Blake <eblake@redhat.com>