virNodeAllocPages: Disallow RO connection

Due to a missing check the API can be successfully called even if
the connection is ReadOnly. Fortunately, the API hasn't been
released yet, so there's no need for a CVE.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/libvirt.c

@@ -21893,6 +21893,7 @@ virNodeAllocPages(virConnectPtr conn,
     virResetLastError();
 
     virCheckConnectReturn(conn, -1);
+    virCheckReadOnlyGoto(conn->flags, error);
     virCheckNonZeroArgGoto(npages, error);
     virCheckNonNullArgGoto(pageSizes, error);
     virCheckNonNullArgGoto(pageCounts, error);