[package] get the enable/disable ipv6 configure option from the build system, do not override it locally

git-svn-id: svn://svn.openwrt.org/openwrt/packages@17009 3c298f89-4303-0410-b956-a3cf2f4a3e73

net/tcpdump/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=tcpdump
 PKG_VERSION:=3.9.8
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://www.tcpdump.org/release/ \
@@ -30,7 +30,6 @@ endef
 
 define Build/Configure
 	$(call Build/Configure/Default, \
-		--enable-ipv6 \
 		--without-crypto \
 		, \
 		BUILD_CC="$(TARGET_CC)" \