Fix buffer_copy

boost::asio::buffer_copy returns an integer of the number of values
copied.  Some static analysis tools mark that value as nodiscard,
although it should never fail.  Audit all uses of buffer_copy, and make
sure that they're using the return value.   In theory this should have
no change on the behavior.

Change-Id: I6af39b5347954c2932cf3d4e48e96ff9ae01583a
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/include/kvm_websocket.hpp b/include/kvm_websocket.hpp
index 0089ae3..df13a67 100644
--- a/include/kvm_websocket.hpp
+++ b/include/kvm_websocket.hpp
@@ -52,11 +52,11 @@
 
         BMCWEB_LOG_DEBUG("conn:{}, Read {} bytes from websocket", logPtr(&conn),
                          data.size());
-        boost::asio::buffer_copy(inputBuffer.prepare(data.size()),
-                                 boost::asio::buffer(data));
+        size_t copied = boost::asio::buffer_copy(
+            inputBuffer.prepare(data.size()), boost::asio::buffer(data));
         BMCWEB_LOG_DEBUG("conn:{}, Committing {} bytes from websocket",
-                         logPtr(&conn), data.size());
-        inputBuffer.commit(data.size());
+                         logPtr(&conn), copied);
+        inputBuffer.commit(copied);
 
         BMCWEB_LOG_DEBUG("conn:{}, inputbuffer size {}", logPtr(&conn),
                          inputBuffer.size());