package/libvirtd: fix recursive dependency in Kconfig

Commit 4dff1be05e90 (package/libvirt: libvirtd needs C++ for nmap-ncat)
introduce a recursive dependency (really: a circular dependency):

    package/busybox/Config.in:33:error: recursive dependency detected!
    package/busybox/Config.in:33:   symbol BR2_PACKAGE_BUSYBOX_SHOW_OTHERS is selected by BR2_PACKAGE_EBTABLES_UTILS_SAVE
    package/ebtables/Config.in:11:  symbol BR2_PACKAGE_EBTABLES_UTILS_SAVE depends on BR2_PACKAGE_EBTABLES
    package/ebtables/Config.in:1:   symbol BR2_PACKAGE_EBTABLES is selected by BR2_PACKAGE_LIBVIRT_DAEMON
    package/libvirt/Config.in:44:   symbol BR2_PACKAGE_LIBVIRT_DAEMON depends on BR2_PACKAGE_NETCAT_OPENBSD
    package/netcat-openbsd/Config.in:1:     symbol BR2_PACKAGE_NETCAT_OPENBSD depends on BR2_PACKAGE_BUSYBOX_SHOW_OTHERS

As usual with this kind of circular depednency, it is not trivial to see
what the real cuplrit is, or where to cut the circle.

A simple solution in this case is to drop the C++ dependency, and switch
the netcat-openbsd and nmap-ncat dependencies conditions.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/libvirt/Config.in

@@ -44,15 +44,13 @@ if BR2_PACKAGE_LIBVIRT
 config BR2_PACKAGE_LIBVIRT_DAEMON
 	bool "libvirtd"
 	default y
-	depends on BR2_INSTALL_LIBSTDCPP || BR2_PACKAGE_NETCAT_OPENBSD # nmap
 	select BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
 	select BR2_PACKAGE_DNSMASQ
 	select BR2_PACKAGE_EBTABLES
 	select BR2_PACKAGE_IPTABLES
 	select BR2_PACKAGE_IPROUTE2
 	# These are required because there is no way to unequivocally select a modern netcat
-	select BR2_PACKAGE_NMAP      if !BR2_PACKAGE_NETCAT_OPENBSD
-	select BR2_PACKAGE_NMAP_NCAT if !BR2_PACKAGE_NETCAT_OPENBSD
+	select BR2_PACKAGE_NETCAT_OPENBSD if !BR2_PACKAGE_NMAP_NCAT
 	select BR2_PACKAGE_RADVD
 	help
 	  Build the libvirt daemon (libvirtd) otherwise build only the