fix debug builds of libtorrent.so

Jamfile

@@ -243,6 +243,12 @@ rule building ( properties * )
 		|| <toolset>gcc in $(properties)
 		|| <toolset>clang in $(propertoes) )
 		&& <link>shared in $(properties)
+		# on GCC, enabling debugging in libstdc++
+		# breaks the ABI and its ability to appear
+		# in shared object interfaces, so when it's
+		# enabled, just export everything (since we're)
+		# probably not a production build anyway
+		&& !<debug-iterators>on in $(properties)
 	{
 		# hide non-external symbols
 		# use ms-compat because boost.asio (as of 1.47.0