util: error: Fix error message strings to play well with additional info
util: error: Fix error message strings to play well with additional info

Additional information for an error message is either in form of a
string or empty. Fix two offenders. One used %d as the format modifier
and the second one  always expected a string.

Thankfully, neither of the offenders are currently in effect.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Erik Skultety <2c14d38fa47c8799f1b9c16280abe27f8edfec6e@redhat.com>

eskultety/libvirt,eskultety/libvirt,nertpinx/libvirt,jfehlig/libvirt,libvirt/libvirt,andreabolognani/libvirt,eskultety/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,zippy2/libvirt,zippy2/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jardasgit/libvirt,jfehlig/libvirt,zippy2/libvirt,crobinso/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,crobinso/libvirt,andreabolognani/libvirt,olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,libvirt/libvirt,jardasgit/libvirt,crobinso/libvirt,eskultety/libvirt,nertpinx/libvirt,eskultety/libvirt,olafhering/libvirt,jardasgit/libvirt,andreabolognani/libvirt