Cocoa: No NSWindowStyleMaskResizable in fullscreen

On macOS 10.15 Catalina and earlier, not having the resizable bit
cleared in NSWindowStyleMask in fullscreen leads to windows minimising
when clicked anywhere in the content area.

On all tested macOS versions it also causes the fullscreen window to be
resizable by the user.

Regression introduced by 0d599026d0.

Fixes #2377
Closes #2405

src/cocoa_window.m

@@ -1284,7 +1284,7 @@ void _glfwSetWindowMonitorCocoa(_GLFWwindow* window,
 
     if (window->monitor)
     {
-        styleMask &= ~(NSWindowStyleMaskTitled | NSWindowStyleMaskClosable);
+        styleMask &= ~(NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskResizable);
         styleMask |= NSWindowStyleMaskBorderless;
     }
     else