Platform: WindolessGlxApplication::Configuration can be a POD.

No need to create symbols for empty constructor/destructor.

src/Platform/WindowlessGlxApplication.cpp

@@ -119,7 +119,4 @@ WindowlessGlxApplication::~WindowlessGlxApplication() {
     glXDestroyContext(display, context);
 }
 
-WindowlessGlxApplication::Configuration::Configuration() = default;
-WindowlessGlxApplication::Configuration::~Configuration() = default;
-
 }}

src/Platform/WindowlessGlxApplication.h

@@ -134,8 +134,7 @@ class WindowlessGlxApplication {
 */
 class WindowlessGlxApplication::Configuration {
     public:
-        /*implicit*/ Configuration();
-        ~Configuration();
+        constexpr /*implicit*/ Configuration() {}
 };
 
 /** @hideinitializer