Wayland: Fix reporting of monitor scale changes

Content scale events would be emitted when a window surface entered or
left an output, but not when one of a window's current outputs had its
scale changed.

(cherry picked from commit e37ba80b13)

README.md

@@ -172,6 +172,8 @@ information on what to include when reporting a bug.
    changed
  - [Wayland] Bugfix: `glfwTerminate` would segfault if any monitor had changed
    scale
+ - [Wayland] Bugfix: Window content scale events were not emitted when monitor
+   scale changed
 
 
 ## Contact

src/wl_monitor.c

@@ -111,6 +111,18 @@ static void outputHandleScale(void* userData,
     struct _GLFWmonitor* monitor = userData;
 
     monitor->wl.scale = factor;
+
+    for (_GLFWwindow* window = _glfw.windowListHead; window; window = window->next)
+    {
+        for (int i = 0; i < window->wl.monitorsCount; i++)
+        {
+            if (window->wl.monitors[i] == monitor)
+            {
+                _glfwUpdateContentScaleWayland(window);
+                break;
+            }
+        }
+    }
 }
 
 #ifdef WL_OUTPUT_NAME_SINCE_VERSION

src/wl_platform.h

@@ -358,6 +358,7 @@ typedef struct _GLFWcursorWayland
 } _GLFWcursorWayland;
 
 void _glfwAddOutputWayland(uint32_t name, uint32_t version);
+void _glfwUpdateContentScaleWayland(_GLFWwindow* window);
 GLFWbool _glfwInputTextWayland(_GLFWwindow* window, uint32_t scancode);
 
 void _glfwAddSeatListenerWayland(struct wl_seat* seat);

src/wl_window.c

@@ -376,7 +376,7 @@ static void resizeWindow(_GLFWwindow* window)
     wl_surface_commit(window->wl.decorations.bottom.surface);
 }
 
-static void checkScaleChange(_GLFWwindow* window)
+void _glfwUpdateContentScaleWayland(_GLFWwindow* window)
 {
     if (_glfw.wl.compositorVersion < WL_SURFACE_SET_BUFFER_SCALE_SINCE_VERSION)
         return;
@@ -414,7 +414,7 @@ static void surfaceHandleEnter(void* userData,
 
     window->wl.monitors[window->wl.monitorsCount++] = monitor;
 
-    checkScaleChange(window);
+    _glfwUpdateContentScaleWayland(window);
 }
 
 static void surfaceHandleLeave(void* userData,
@@ -435,7 +435,7 @@ static void surfaceHandleLeave(void* userData,
     }
     window->wl.monitors[--window->wl.monitorsCount] = NULL;
 
-    checkScaleChange(window);
+    _glfwUpdateContentScaleWayland(window);
 }
 
 static const struct wl_surface_listener surfaceListener =