Fix some warnings

1. Enabled Meson options to treat warnings as errors.
2. Removed unused variable in vpd_tool_impl.cpp.
3. Fix for unused variable warning in vpdecc & vpd manager files.

Signed-off-by: Priyanga Ramasamy <priyanga24@in.ibm.com>
Change-Id: I59fab47fe394b2934d6050d9db78c68b7e471503
diff --git a/vpd-manager/manager_main.cpp b/vpd-manager/manager_main.cpp
index 459c9f4..fce02b4 100644
--- a/vpd-manager/manager_main.cpp
+++ b/vpd-manager/manager_main.cpp
@@ -7,7 +7,7 @@
 #include <iostream>
 #include <sdbusplus/bus.hpp>
 
-int main(int argc, char* argv[])
+int main(int /*argc*/, char** /*argv*/)
 {
     try
     {