Replace comments with designated initializers

We can finally have the compiler verify that the values go to the
correct struct member.

With this commit GLFW no longer compiles with Visual Studio 2012 or
earlier.  If you must compile GLFW on Windows XP, check out MinGW-w64.

Fixes #2465

src/init.c

@@ -49,19 +49,22 @@ static GLFWerrorfun _glfwErrorCallback;
 static GLFWallocator _glfwInitAllocator;
 static _GLFWinitconfig _glfwInitHints =
 {
-    GLFW_TRUE,      // hat buttons
-    GLFW_ANGLE_PLATFORM_TYPE_NONE, // ANGLE backend
-    GLFW_ANY_PLATFORM, // preferred platform
-    NULL,           // vkGetInstanceProcAddr function
+    .hatButtons = GLFW_TRUE,
+    .angleType = GLFW_ANGLE_PLATFORM_TYPE_NONE,
+    .platformID = GLFW_ANY_PLATFORM,
+    .vulkanLoader = NULL,
+    .ns =
     {
-        GLFW_TRUE,  // macOS menu bar
-        GLFW_TRUE   // macOS bundle chdir
+        .menubar = GLFW_TRUE,
+        .chdir = GLFW_TRUE
     },
+    .x11 =
     {
-        GLFW_TRUE,  // X11 XCB Vulkan surface
+        .xcbVulkanSurface = GLFW_TRUE,
     },
+    .wl =
     {
-        GLFW_WAYLAND_PREFER_LIBDECOR // Wayland libdecor mode
+        .libdecorMode = GLFW_WAYLAND_PREFER_LIBDECOR
     },
 };