Fix moves/forward

Clang has new checks for std::move/std::forward correctness, which
catches quite a few "wrong" things where we were making copies of
callback handlers.

Unfortunately, the lambda syntax of

callback{std::forward<Callback>(callback)}

in a capture confuses it, so change usages to
callback = std::forward<Callback>(callback)

to be consistent.

Tested: Redfish service validator passes.

Change-Id: I7a111ec00cf78ecb7d5f5b102c786c1c14d74384
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/include/async_resolve.hpp b/include/async_resolve.hpp
index 805fbad..798c3e8 100644
--- a/include/async_resolve.hpp
+++ b/include/async_resolve.hpp
@@ -83,7 +83,7 @@
         uint64_t flag = 0;
         crow::connections::systemBus->async_method_call(
             [host{std::string(host)}, portNum,
-             handler{std::forward<ResolveHandler>(handler)}](
+             handler = std::forward<ResolveHandler>(handler)](
                 const boost::system::error_code& ec,
                 const std::vector<
                     std::tuple<int32_t, int32_t, std::vector<uint8_t>>>& resp,