Add GPU usage daemon

Works for AMD GPUs only using the amdgpu_top utility

config/awesome/evil/gpu.lua

@@ -0,0 +1,16 @@
+-- Provides:
+-- evil::gpu
+--      used percentage (integer from 0 to 100)
+local awful = require("awful")
+
+local update_interval = 5
+
+-- For AMD GPUs
+local gpu_script = [[
+  sh -c "
+  amdgpu_top -gm --single | awk '/average_gfx_activity/ {print substr($2, 1, length($2)-1)}'
+  "]]
+
+awful.widget.watch(gpu_script, update_interval, function(_, stdout)
+    awesome.emit_signal("evil::gpu", tonumber(stdout))
+end)