Add bundled(gnulib) to RPM specfile

According to Fedora guidelines, because we bundle gnulib we
need to add a virtual Provides: bundled(gnulib).

https://fedoraproject.org/wiki/Packaging:No_Bundled_Libraries#Requirement_if_you_bundle

libvirt.spec.in

@@ -460,6 +460,8 @@ BuildRequires: scrub
 BuildRequires: numad
 %endif
 
+Provides: bundled(gnulib)
+
 %description
 Libvirt is a C toolkit to interact with the virtualization capabilities
 of recent versions of Linux (and other OSes). The main package includes