~ Fix linux build

~ Fix dopler example

examples/DopplerEffect/main.cpp

@@ -70,7 +70,7 @@ int main()
 		std::cout << "Sound position: " << pos << std::endl;
 
 		// Si la position de la source atteint une certaine position, ou si l'utilisateur appuie sur echap
-		if (pos.x > Nz::Vector3f::Left().x*-50.f || Nz::Keyboard::IsKeyPressed(Nz::Keyboard::Escape))
+		if (pos.x > Nz::Vector3f::Left().x*-50.f || Nz::Keyboard::IsKeyPressed(Nz::Keyboard::VKey::Escape))
 			sound.Stop(); // On arrête le son (Stoppant également la boucle)
 
 		clock.Restart();

src/Nazara/Renderer/Context.cpp

@@ -14,6 +14,10 @@
 
 #if defined(NAZARA_PLATFORM_SDL2)
 	#include <Nazara/Renderer/SDL2/ContextImpl.hpp>
+
+	#if defined(NAZARA_PLATFORM_LINUX)
+		#define CALLBACK
+	#endif
 #elif defined(NAZARA_PLATFORM_WINDOWS)
 	#include <Nazara/Renderer/Win32/ContextImpl.hpp>
 #elif defined(NAZARA_PLATFORM_GLX)