X11: Prevent BadWindow when creating small windows

The glfwCreateWindow function ensures that the width and height are
at least greater or equal than zero, but on X11 it is invalid to
create a window with dimensions that equal zero, see [1].

This change ensures that the dimensions passed to XCreateWindow are
at least 1 by 1.

This issue was detected in [2], where a call to glfwCreateWindow
was done to request a 1x1 window, with a _glfw.x11.contentScaleX of
less than 1.0 (0.958333) this results in a request for a 0x0 window
which then causes an BadWindow error from X11.

[1]: https://gitlab.freedesktop.org/xorg/lib/libx11/-/blob/e003f52661679e95b51ff24e317af6178fe2a73c/specs/libX11/CH03.xml#L1333-1337
[2]: https://github.com/WerWolv/ImHex/pull/2390

src/x11_window.c

@@ -576,6 +576,10 @@ static GLFWbool createNativeWindow(_GLFWwindow* window,
         height *= _glfw.x11.contentScaleY;
     }
 
+    // The dimensions must be nonzero, or a BadValue error results.
+    width = _glfw_max(1, width);
+    height = _glfw_max(1, height);
+
     int xpos = 0, ypos = 0;
 
     if (wndconfig->xpos != GLFW_ANY_POSITION && wndconfig->ypos != GLFW_ANY_POSITION)