use ipv6 preference only when netinet headers not used (entware with musl workaround)'

Signed-off-by: R4SAS <r4sas@i2pmail.org>

libi2pd/NTCP2.cpp

@@ -23,7 +23,7 @@
 #include "HTTP.h"
 #include "util.h"
 
-#ifdef __linux__
+#if defined(__linux__) && !defined(_NETINET_IN_H)
 	#include <linux/in6.h>
 #endif
 
@@ -757,7 +757,7 @@ namespace transport
 		if (IsTerminated ()) return;
 #ifdef __linux__
 		const int one = 1;
-    	setsockopt(m_Socket.native_handle(), IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
+		setsockopt(m_Socket.native_handle(), IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
 #endif
 		boost::asio::async_read (m_Socket, boost::asio::buffer(&m_NextReceivedLen, 2), boost::asio::transfer_all (),
 			std::bind(&NTCP2Session::HandleReceivedLength, shared_from_this (), std::placeholders::_1, std::placeholders::_2));
@@ -1243,7 +1243,7 @@ namespace transport
 							m_NTCP2V6Acceptor->open (boost::asio::ip::tcp::v6());
 							m_NTCP2V6Acceptor->set_option (boost::asio::ip::v6_only (true));
 							m_NTCP2V6Acceptor->set_option (boost::asio::socket_base::reuse_address (true));
-#ifdef __linux__
+#if defined(__linux__) && !defined(_NETINET_IN_H)
 							if (!m_Address6 && !m_YggdrasilAddress) // only if not binded to address
 							{
 								// Set preference to use public IPv6 address -- tested on linux, not works on windows, and not tested on others

libi2pd/SSU.cpp

@@ -15,7 +15,7 @@
 #include "util.h"
 #include "SSU.h"
 
-#ifdef __linux__
+#if defined(__linux__) && !defined(_NETINET_IN_H)
 	#include <linux/in6.h>
 #endif
 
@@ -68,7 +68,7 @@ namespace transport
 			m_SocketV6.set_option (boost::asio::ip::v6_only (true));
 			m_SocketV6.set_option (boost::asio::socket_base::receive_buffer_size (SSU_SOCKET_RECEIVE_BUFFER_SIZE));
 			m_SocketV6.set_option (boost::asio::socket_base::send_buffer_size (SSU_SOCKET_SEND_BUFFER_SIZE));
-#ifdef __linux__
+#if defined(__linux__) && !defined(_NETINET_IN_H)
 			if (m_EndpointV6.address() == boost::asio::ip::address().from_string("::")) // only if not binded to address
 			{
 				// Set preference to use public IPv6 address -- tested on linux, not works on windows, and not tested on others