core: detect screen off

Use the DPMS extension to detect if screen is turned off, and unredirect
if it is. This also helps working around the problem where OpenGL
buffers lose data when screen is turned off, causing screen to flicker
later when it turns back on if use-damage is enabled.

Unfortunately the DPMS extension doesn't define an event, so we have to
periodically poll the screen state.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

.github/workflows/codeql-analysis.yml

@@ -36,7 +36,7 @@ jobs:
         languages: ${{ matrix.language }}
 
     # Install dependencies
-    - run: sudo apt update && sudo apt install libxext-dev libxcb1-dev libxcb-damage0-dev libxcb-xfixes0-dev libxcb-shape0-dev libxcb-render-util0-dev libxcb-render0-dev libxcb-randr0-dev libxcb-composite0-dev libxcb-image0-dev libxcb-present-dev libxcb-xinerama0-dev libxcb-glx0-dev libpixman-1-dev libdbus-1-dev libconfig-dev libgl1-mesa-dev  libpcre2-dev  libevdev-dev uthash-dev libev-dev libx11-xcb-dev meson ninja-build
+    - run: sudo apt update && sudo apt install libxext-dev libxcb1-dev libxcb-dpms0-dev libxcb-damage0-dev libxcb-xfixes0-dev libxcb-shape0-dev libxcb-render-util0-dev libxcb-render0-dev libxcb-randr0-dev libxcb-composite0-dev libxcb-image0-dev libxcb-present-dev libxcb-xinerama0-dev libxcb-glx0-dev libpixman-1-dev libdbus-1-dev libconfig-dev libgl1-mesa-dev  libpcre2-dev  libevdev-dev uthash-dev libev-dev libx11-xcb-dev meson ninja-build
       if: ${{ matrix.language == 'cpp' }}
 
     # Autobuild