Fix compiler warnings about unused initialized variables, and unused formal parameters

Signed-off-by: Daniela Engert <dani@ngrt.de>

examples/constexpr14_namespace_check.cpp

@@ -54,7 +54,7 @@ constexpr bool in_namespace(const char (&ns)[N]) noexcept {
 namespace my_project {
     struct serializer {
         template <class T>
-        void serialize(const T& value) {
+        void serialize(const T&) {
             static_assert(
                 in_namespace<T>("my_project::types") || in_namespace<T>("my_project::types_ext"),
                 "Only types from namespaces `my_project::types` and `my_project::types_ext` are allowed to be serialized using `my_project::serializer`"

examples/constexpr14_sort_check.cpp

@@ -55,7 +55,7 @@ constexpr bool is_asc_sorted(types<Lhs, Rhs, TN...>) noexcept {
 
 // Using the newly created `is_asc_sorted` trait:
 template <class... T>
-void do_something(const types<T...>& t) noexcept {
+void do_something(const types<T...>&) noexcept {
     static_assert(
         is_asc_sorted( types<T...>() ),
         "T... for do_something(const types<T...>& t) must be sorted ascending"

examples/registry.cpp

@@ -40,6 +40,7 @@ int main() {
 
     // Const, volatile and reference will be striped from the type:
     bool is_inserted = types.insert(boost::typeindex::type_id<const int>()).second;
+	(void)is_inserted;
     assert(!is_inserted);
     assert(types.erase(boost::typeindex::type_id<float&>()) == 1);
     

examples/user_defined_typeinfo.cpp

@@ -53,6 +53,7 @@ int main() {
 */
     my_struct str;
     my_class& reference = str;
+	(void)reference;
     assert(my_type_index::type_id<my_struct>() == my_type_index::type_id_runtime(reference));
 //][/type_index_my_type_index_type_id_runtime_test]
 

examples/user_defined_typeinfo.hpp

@@ -47,11 +47,20 @@ namespace my_namespace { namespace detail {
     template <> struct typenum<my_classes>{ enum {value = 3}; };
     template <> struct typenum<my_string>{  enum {value = 4}; };
 
+#ifdef BOOST_MSVC
+#pragma warning(push)
+#pragma warning(disable: 4510 4512 4610) // non-copyable non-constructable type
+#endif
+
     // my_typeinfo structure is used to save type number
     struct my_typeinfo {
         const char* const type_;
     };
 
+#ifdef BOOST_MSVC
+#pragma warning(pop)
+#endif
+
     const my_typeinfo infos[5] = {
         {"void"}, {"my_class"}, {"my_struct"}, {"my_classes"}, {"my_string"}
     };

include/boost/type_index/stl_type_index.hpp

@@ -268,6 +268,7 @@ inline stl_type_index stl_type_index::type_id_with_cvr() BOOST_NOEXCEPT {
 
 template <class T>
 inline stl_type_index stl_type_index::type_id_runtime(const T& value) BOOST_NOEXCEPT {
+    (void)value;
 #ifdef BOOST_NO_RTTI
     return value.boost_type_index_type_id_runtime_();
 #else