linknx: needs argp-standalone on uClibc

Fixes:
http://autobuild.buildroot.net/results/b27/b27c4b0822494fb393a5e28b8febd063222bd83f/
http://autobuild.buildroot.net/results/9db/9db2cc9fe6ddfda5663251872fdba00998020fce/
http://autobuild.buildroot.net/results/465/465328d0aa6b5f4b36903e2a4bc41d4ddd343db8/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/linknx/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_LINKNX
 	bool "linknx"
 	select BR2_PACKAGE_LIBPTHSEM
+	select BR2_PACKAGE_ARGP_STANDALONE if BR2_TOOLCHAIN_USES_UCLIBC
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_USE_MMU # libpthsem
 	help

package/linknx/linknx.mk

@@ -15,7 +15,7 @@ LINKNX_CONF_OPTS = \
 	--with-pth=$(STAGING_DIR)/usr \
 	--disable-smtp
 
-LINKNX_DEPENDENCIES = libpthsem
+LINKNX_DEPENDENCIES = libpthsem $(if $(BR2_PACKAGE_ARGP_STANDALONE),argp-standalone)
 
 ifeq ($(BR2_PACKAGE_MYSQL),y)
 LINKNX_CONF_OPTS += --with-mysql=$(STAGING_DIR)/usr/bin/mysql_config