Moved OpenGL init and terminate to opengl module.

src/x11_platform.h

@@ -283,6 +283,8 @@ GLFWGLOBAL struct {
 void _glfwInitTimer(void);
 
 // OpenGL support
+int _glfwInitOpenGL(void);
+void _glfwTerminateOpenGL(void);
 int _glfwCreateContext(_GLFWwindow* window,
                        const _GLFWwndconfig* wndconfig,
                        const _GLFWfbconfig* fbconfig);