libtorrent: Enable IPv6 and clean up Makefile

This was not touched since I took maintainership.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/libtorrent/Makefile

@@ -9,14 +9,19 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libtorrent
 PKG_VERSION:=0.13.7
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/rakshasa/libtorrent/tar.gz/v$(PKG_VERSION)?
 PKG_HASH:=86b4b1753385aaddf9e59ad94f1292eee5102139eb57520e84d1af2f04693708
 
+PKG_MAINTAINER:=Rosen Penev <rosenp@gmail.com>
+PKG_LICENSE:=GPL-2.0-or-later
+PKG_LICENSE_FILES:=COPYING
+
 PKG_FIXUP:=autoreconf
-PKG_BUILD_PARALLEL:=1
 PKG_INSTALL:=1
+PKG_BUILD_PARALLEL:=1
 
 include $(INCLUDE_DIR)/package.mk
 
@@ -26,7 +31,6 @@ define Package/libtorrent
   TITLE:=Rakshasa's BitTorrent library
   URL:=https://rakshasa.github.io/rtorrent/
   DEPENDS:=+libopenssl +libsigcxx +zlib
-  MAINTAINER:=Rosen Penev <rosenp@gmail.com>
 endef
 
 define Package/libtorrent/description
@@ -37,17 +41,17 @@ define Package/libtorrent/description
  official client.
 endef
 
-TARGET_LDFLAGS += $(LIBGCC_S)
-
-CONFIGURE_ARGS+= \
+CONFIGURE_ARGS += \
 	--enable-shared \
 	--enable-static \
 	--enable-aligned \
-	--disable-debug \
 	--enable-openssl \
+	--disable-debug \
 	--disable-instrumentation \
+	--with-epoll \
 	--with-zlib=$(STAGING_DIR)/usr \
-	--disable-ipv6
+	--without-kqueue \
+	$(DISABLE_IPV6)
 
 define Build/InstallDev
 	$(INSTALL_DIR) $(1)/usr/include