Fix -Wextra-semi warnings

Closes #1440.

README.md

@@ -122,6 +122,7 @@ information on what to include when reporting a bug.
  - Bugfix: The CMake config-file package used an absolute path and was not
    relocatable (#1470)
  - Bugfix: Video modes with a duplicate screen area were discarded (#1555,#1556)
+ - Bugfix: Fix -Wextra-semi compilation warning (#1440)
  - [Win32] Bugfix: `GLFW_INCLUDE_VULKAN` plus `VK_USE_PLATFORM_WIN32_KHR` caused
    symbol redefinition (#1524)
  - [Win32] Bugfix: The cursor position event was emitted before its cursor enter

src/cocoa_joystick.h

@@ -30,7 +30,7 @@
 #include <IOKit/hid/IOHIDKeys.h>
 
 #define _GLFW_PLATFORM_JOYSTICK_STATE         _GLFWjoystickNS ns
-#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE
+#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE struct { int dummyJoystick; }
 
 #define _GLFW_PLATFORM_MAPPING_NAME "Mac OS X"
 

src/null_joystick.h

@@ -24,8 +24,8 @@
 //
 //========================================================================
 
-#define _GLFW_PLATFORM_JOYSTICK_STATE         int nulljs
-#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE int nulljs
+#define _GLFW_PLATFORM_JOYSTICK_STATE         struct { int dummyJoystick; }
+#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE struct { int dummyLibraryJoystick; }
 
 #define _GLFW_PLATFORM_MAPPING_NAME ""
 

src/null_platform.h

@@ -29,13 +29,13 @@
 
 #define _GLFW_PLATFORM_WINDOW_STATE _GLFWwindowNull null
 
-#define _GLFW_PLATFORM_CONTEXT_STATE
-#define _GLFW_PLATFORM_MONITOR_STATE
-#define _GLFW_PLATFORM_CURSOR_STATE
-#define _GLFW_PLATFORM_LIBRARY_WINDOW_STATE
-#define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE
-#define _GLFW_EGL_CONTEXT_STATE
-#define _GLFW_EGL_LIBRARY_CONTEXT_STATE
+#define _GLFW_PLATFORM_CONTEXT_STATE         struct { int dummyContext; }
+#define _GLFW_PLATFORM_MONITOR_STATE         struct { int dummyMonitor; }
+#define _GLFW_PLATFORM_CURSOR_STATE          struct { int dummyCursor; }
+#define _GLFW_PLATFORM_LIBRARY_WINDOW_STATE  struct { int dummyLibraryWindow; }
+#define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE struct { int dummyLibraryContext; }
+#define _GLFW_EGL_CONTEXT_STATE              struct { int dummyEGLContext; }
+#define _GLFW_EGL_LIBRARY_CONTEXT_STATE      struct { int dummyEGLLibraryContext; }
 
 #include "osmesa_context.h"
 #include "posix_time.h"

src/win32_joystick.h

@@ -25,7 +25,7 @@
 //========================================================================
 
 #define _GLFW_PLATFORM_JOYSTICK_STATE         _GLFWjoystickWin32 win32
-#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE int dummy
+#define _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE struct { int dummyLibraryJoystick; }
 
 #define _GLFW_PLATFORM_MAPPING_NAME "Windows"
 

src/wl_platform.h

@@ -75,8 +75,8 @@ typedef VkBool32 (APIENTRY *PFN_vkGetPhysicalDeviceWaylandPresentationSupportKHR
 #define _GLFW_PLATFORM_MONITOR_STATE        _GLFWmonitorWayland wl
 #define _GLFW_PLATFORM_CURSOR_STATE         _GLFWcursorWayland  wl
 
-#define _GLFW_PLATFORM_CONTEXT_STATE
-#define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE
+#define _GLFW_PLATFORM_CONTEXT_STATE         struct { int dummyContext; }
+#define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE struct { int dummyLibraryContext; }
 
 struct wl_cursor_image {
     uint32_t width;