bytes_ostream: increase max chunk size to 128 kB

128 kB is the size of the LSA segment and therefore the default size of
any kind of chunks, fragments and buffers.

Message-Id: <20180709155615.22500-1-pdziepak@scylladb.com>

bytes_ostream.hh

@@ -38,7 +38,7 @@ class bytes_ostream {
 public:
     using size_type = bytes::size_type;
     using value_type = bytes::value_type;
-    static constexpr size_type max_chunk_size() { return 16 * 1024; }
+    static constexpr size_type max_chunk_size() { return 128 * 1024; }
 private:
     static_assert(sizeof(value_type) == 1, "value_type is assumed to be one byte long");
     struct chunk {