shadowsocks-libev: configure options for release build

- It's a common practice that assert should be ignored in release build
 - Whether to enable ssp should be decided by the config of build system

This was taken from Makefile in shadowsocks/openwrt-shadowsocks.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

net/shadowsocks-libev/Makefile

@@ -19,7 +19,7 @@ include $(TOPDIR)/rules.mk
 #
 PKG_NAME:=shadowsocks-libev
 PKG_VERSION:=3.0.7
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://github.com/shadowsocks/shadowsocks-libev/releases/download/v$(PKG_VERSION)
@@ -110,6 +110,8 @@ endef
 CONFIGURE_ARGS += \
 	--disable-documentation \
 	--disable-silent-rules \
+	--disable-assert \
+	--disable-ssp \
 
 $(eval $(call BuildPackage,shadowsocks-libev-config))
 $(eval $(call BuildPackage,shadowsocks-libev-ss-rules))