libvirt-devel should only require libvirt-client

There's a long known issue where if you install libvirt in a guest,
the default virtual network will conflict with the default virtual
network in the host.

That's one of the reasons we have the libvirt-client RPM - it allows
you to install the client library without having the host side
installed.

Rich Jones points out that if you install libvirt-devel in a guest,
then you get libvirtd installed and the network conflict:

  https://bugzilla.redhat.com/531200

libvirt-devel should only require libvirt-client - e.g. nothing in
the devel package pertains to anything in the libvirt RPM. The Fedora
packaging guidelines say:

  https://fedoraproject.org/wiki/Packaging/Guidelines#Devel_Packages

  Devel packages must require the base package using a fully versioned
  dependency ...

But for all intents and purposes, libvirt-client is our base RPM.

* libvirt.spec.in: make libvirt-devel require libvirt-client

libvirt.spec.in

@@ -341,7 +341,7 @@ virtualization capabilities of recent versions of Linux (and other OSes).
 %package devel
 Summary: Libraries, includes, etc. to compile with the libvirt library
 Group: Development/Libraries
-Requires: libvirt = %{version}-%{release}
+Requires: libvirt-client = %{version}-%{release}
 Requires: pkgconfig
 %if %{with_xen}
 Requires: xen-devel