bind: Allow packages to be built with optional filter-aaaa option

Signed-off-by: Noah Meyerhans <frodo@morgul.net>

net/bind/Config.in

+if PACKAGE_bind-server
+
+config BIND_ENABLE_FILTER_AAAA
+	bool
+	default n
+	prompt "Enable filtering of AAAA records returned to the client"
+	help
+		BIND 9 has an option to filter AAAA (IPv6 address) records
+		returned to the client based on the transport used for the
+		query, and other filtering conditions. This filtering does
+		not affect the recursive queries made by the server (if
+		any) as a result of the client request.
+
+		Additional details are available at
+		https://kb.isc.org/article/AA-00576/0/Filter-AAAA-option-in-BIND-9-.html
+
+endif

net/bind/Makefile

 
 PKG_NAME:=bind
 PKG_VERSION:=9.9.8-P3
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 USERID:=bind=57:bind=57
 
 PKG_MAINTAINER := Noah Meyerhans <frodo@morgul.net>
 
 PKG_INSTALL:=1
 
-PKG_CONFIG_DEPENDS := CONFIG_OPENSSL_WITH_EC
+PKG_CONFIG_DEPENDS := \
+	CONFIG_OPENSSL_WITH_EC \
+	CONFIG_BIND_ENABLE_FILTER_AAAA
 
 include $(INCLUDE_DIR)/package.mk
 
   TITLE+= DNS server
 endef
 
+define Package/bind-server/config
+	source "$(SOURCE)/Config.in"
+endef
+
 define Package/bind-client
   $(call Package/bind/Default)
   TITLE+= dynamic DNS client
 	--with-ecdsa=$(if $(CONFIG_OPENSSL_WITH_EC),yes,no) \
 	--with-readline=no
 
+ifdef CONFIG_BIND_ENABLE_FILTER_AAAA
+	CONFIGURE_ARGS += \
+		--enable-filter-aaaa
+endif
+
 CONFIGURE_VARS += \
 	BUILD_CC="$(TARGET_CC)" \