Fix consuming_buffers value_type (API Change):

This fixes a bug where instantiations of consuming_buffers with
buffer sequence types whose value_type is not const_buffer or
mutable_buffer can cause compilation errors.

The function consumed_buffers is removed.

test/core/consuming_buffers.cpp

@@ -19,6 +19,16 @@ namespace beast {
 class consuming_buffers_test : public beast::unit_test::suite
 {
 public:
+    template<class BufferSequence>
+    static
+    consuming_buffers<BufferSequence>
+    consumed_buffers(BufferSequence const& bs, std::size_t n)
+    {
+        consuming_buffers<BufferSequence> cb(bs);
+        cb.consume(n);
+        return cb;
+    }
+
     template<class Buffers1, class Buffers2>
     static
     bool

test/websocket/utf8_checker.cpp

@@ -283,10 +283,10 @@ public:
             {
                 static std::size_t constexpr size = 3;
                 std::size_t n = s.size();
-                auto cb = consumed_buffers(
-                    boost::asio::const_buffers_1(
-                        s.data(), n), 0);
-                streambuf sb(size);
+                consuming_buffers<
+                    boost::asio::const_buffers_1> cb{
+                        boost::asio::const_buffers_1(s.data(), n)};
+                streambuf sb{size};
                 while(n)
                 {
                     auto const amount = (std::min)(n, size);