rpc: Require dtrace sources to be generated first
rpc: Require dtrace sources to be generated first

The virt_socket_lib is built from virnetsocket.c (among others).
But this file includes virprobe.h which includes libvirt_probes.h
which is a generated file. But this dependency is not recorded in
meson which may lead to a failed build.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

crobinso/libvirt,libvirt/libvirt,crobinso/libvirt,jfehlig/libvirt,olafhering/libvirt,zippy2/libvirt,olafhering/libvirt,libvirt/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,crobinso/libvirt,jfehlig/libvirt,crobinso/libvirt