minor comment fix: adjust it to reflect the change from boost-asio to non-boost asio.

git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@2727 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/cc/session.cc

@@ -134,7 +134,7 @@ SessionImpl::readData(void* data, size_t datalen) {
     try {
         asio::read(socket_, asio::buffer(data, datalen));
     } catch (const asio::system_error& asio_ex) {
-        // to hide boost specific exceptions, we catch them explicitly
+        // to hide ASIO specific exceptions, we catch them explicitly
         // and convert it to SessionError.
         isc_throw(SessionError, "ASIO read failed: " << asio_ex.what());
     }