Add missing header <cstdarg> for va_list.

* Fix building on OpenBSD.

include/libtorrent/aux_/session_interface.hpp

@@ -52,6 +52,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef TORRENT_DISABLE_LOGGING
 #include <boost/shared_ptr.hpp>
+#include <cstdarg> // for va_list
 #endif
 
 #ifdef TORRENT_USE_OPENSSL

src/disk_io_thread.cpp

@@ -62,6 +62,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #if __cplusplus >= 201103L || defined __clang__
 
 #if DEBUG_DISK_THREAD
+#include <cstdarg> // for va_list
 #define DLOG(...) debug_log(__VA_ARGS__)
 #else
 #define DLOG(...) do {} while(false)

src/session_impl.cpp

@@ -107,6 +107,8 @@ POSSIBILITY OF SUCH DAMAGE.
 // for logging stat layout
 #include "libtorrent/stat.hpp"
 
+#include <cstdarg> // for va_list
+
 // for logging the size of DHT structures
 #ifndef TORRENT_DISABLE_DHT
 #include <libtorrent/kademlia/find_data.hpp>