Add CONFIG_FEATURE_SYSLOG which controls whether
bb_xx_msg will ever try to send output to syslog.
Add "select CONFIG_FEATURE_SYSLOG" to relevant applets.
This allows to omit syslog code if we do not have
any syslog-capable applets in the build.

diff --git a/networking/udhcp/Config.in b/networking/udhcp/Config.in
index 01b2902..7732937 100644
--- a/networking/udhcp/Config.in
+++ b/networking/udhcp/Config.in
@@ -6,6 +6,7 @@
 config CONFIG_APP_UDHCPD
 	bool "udhcp Server (udhcpd)"
 	default n
+	select CONFIG_FEATURE_SYSLOG
 	help
 	  uDHCPd is a DHCP server geared primarily toward embedded systems,
 	  while striving to be fully functional and RFC compliant.
@@ -26,6 +27,7 @@
 config CONFIG_APP_UDHCPC
 	bool "udhcp Client (udhcpc)"
 	default n
+	select CONFIG_FEATURE_SYSLOG
 	help
 	  uDHCPc is a DHCP client geared primarily toward embedded systems,
 	  while striving to be fully functional and RFC compliant.
@@ -35,16 +37,6 @@
 
 	  See http://udhcp.busybox.net for further details.
 
-config CONFIG_FEATURE_UDHCP_SYSLOG
-	bool "Log udhcp messages to syslog (instead of stdout)"
-	default n
-	depends on CONFIG_APP_UDHCPD || CONFIG_APP_UDHCPC
-	help
-	  If selected, udhcpd will log all its messages to syslog, otherwise,
-	  it will attempt to log them to stdout.
-
-	  See http://udhcp.busybox.net for further details.
-
 config CONFIG_FEATURE_UDHCP_DEBUG
 	bool "Compile udhcp with noisy debugging messages"
 	default n