X11: check crtcInfo for NULL when polling monitors

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]: e003f52661/specs/libX11/CH03.xml (L1333-1337)
[2]: https://github.com/WerWolv/ImHex/pull/2390

CONTRIBUTORS.md

@@ -282,10 +282,12 @@ video tutorials.
  - Corentin Wallez
  - Torsten Walluhn
  - Patrick Walton
+ - Ivor Wanders
  - Jim Wang
  - Xo Wang
  - Andre Weissflog
  - Jay Weisskopf
+ - Drew Weymouth
  - Frank Wille
  - Andy Williams
  - Joel Winarske

README.md

@@ -145,10 +145,13 @@ information on what to include when reporting a bug.
  - [Wayland] Bugfix: The cursor position was not updated when clicking through
    from a modal to the content area
  - [X11] Bugfix: Running without a WM could trigger an assert (#2593,#2601,#2631)
+ - [X11] Bugfix: Occasional crash when an idle display awakes (#2766) 
  - [Null] Added Vulkan 'window' surface creation via `VK_EXT_headless_surface`
  - [Null] Added EGL context creation on Mesa via `EGL_MESA_platform_surfaceless`
  - [EGL] Allowed native access on Wayland with `GLFW_CONTEXT_CREATION_API` set to
    `GLFW_NATIVE_CONTEXT_API` (#2518)
+ - [X11] Bugfix: Prevent BadWindow when creating small windows with a content scale
+   less than 1 (#2754)
 
 
 ## Contact

src/x11_monitor.c

@@ -151,6 +151,11 @@ void _glfwPollMonitorsX11(void)
             }
 
             XRRCrtcInfo* ci = XRRGetCrtcInfo(_glfw.x11.display, sr, oi->crtc);
+            if (!ci) {
+                XRRFreeOutputInfo(oi);
+                continue;
+            }
+
             if (ci->rotation == RR_Rotate_90 || ci->rotation == RR_Rotate_270)
             {
                 widthMM  = oi->mm_height;

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)