bmcweb: Fix a bunch of warnings

bmcweb classically has not taken a strong opinion on warnings.  With
this commit, that policy is changing, and bmcweb will invoke the best
warnings we are able to enable, and turn on -Werror for all builds.

This is intended to reduce the likelihood of hard-to-debug situations
that the compiler coulve caught early on.

Change-Id: I57474410821e82666b3a108cfd0db7d070e8900a
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/redfish-core/lib/managers.hpp b/redfish-core/lib/managers.hpp
index f9c2f38..0aa4478 100644
--- a/redfish-core/lib/managers.hpp
+++ b/redfish-core/lib/managers.hpp
@@ -785,10 +785,10 @@
             for (auto& step : *steps)
             {
                 double target;
-                double output;
+                double out;
 
                 if (!redfish::json_util::readJson(step, response->res, "Target",
-                                                  target, "Output", output))
+                                                  target, "Output", out))
                 {
                     BMCWEB_LOG_ERROR << "Line:" << __LINE__
                                      << ", Illegal Property "
@@ -796,7 +796,7 @@
                     return CreatePIDRet::fail;
                 }
                 readings.emplace_back(target);
-                outputs.emplace_back(output);
+                outputs.emplace_back(out);
             }
             output["Reading"] = std::move(readings);
             output["Output"] = std::move(outputs);