Removed GLFW_NO_ERROR.

As glfwGetError was removed (due to a race between glfwInit error
reporting and manual TLS setup on OS X), this token has no purpose.

include/GL/glfw3.h

@@ -446,9 +446,6 @@ extern "C" {
 /*! @defgroup errors Error codes
  *  @ingroup error
  *  @{ */
-/*! @brief No error has occurred.
- */
-#define GLFW_NO_ERROR               0
 /*! @brief GLFW has not been initialized.
  */
 #define GLFW_NOT_INITIALIZED        0x00070001

src/init.c

@@ -56,8 +56,6 @@ static const char* getErrorString(int error)
 {
     switch (error)
     {
-        case GLFW_NO_ERROR:
-            return "No error";
         case GLFW_NOT_INITIALIZED:
             return "The GLFW library is not initialized";
         case GLFW_NO_CURRENT_CONTEXT: