Allow a monitor to be created without a name.

src/monitor.c

@@ -175,10 +175,12 @@ void _glfwInputMonitorWindowChange(_GLFWmonitor* monitor, _GLFWwindow* window)
 _GLFWmonitor* _glfwAllocMonitor(const char* name, int widthMM, int heightMM)
 {
     _GLFWmonitor* monitor = calloc(1, sizeof(_GLFWmonitor));
-    monitor->name = strdup(name);
     monitor->widthMM = widthMM;
     monitor->heightMM = heightMM;
 
+    if (name)
+        monitor->name = strdup(name);
+
     return monitor;
 }