Fix C++11 strict string literal const correctness.

src/OpenGL/libGL/Shader.cpp

@@ -197,7 +197,7 @@ void Shader::compile()
 	TranslatorASM *compiler = createCompiler(getType());
 
 	// Ensure we don't pass a nullptr source to the compiler
-	char *source = "\0";
+	const char *source = "\0";
 	if(mSource)
 	{
 		source = mSource;

tests/OGLSimpleCube/OGLSimpleCube.cpp

@@ -37,7 +37,7 @@ Inspired by http://www.cs.rit.edu/~ncs/Courses/570/UserGuide/OpenGLonWin-11.html
 LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
 
 const char *className = "OpenGL";
-char *windowName = "OpenGL Cube";
+const char *windowName = "OpenGL Cube";
 int winX = 0, winY = 0;
 int winWidth = 300, winHeight = 300;
 float angle = 0.1f;