ci: make the v gret steps more robust to slow CI runners

Author: spytheman

.github/workflows/c2v.yml

@@ -121,8 +121,8 @@ jobs:
         id: compare
         continue-on-error: true
         run: |
-          Xvfb $DISPLAY -screen 0 800x600x24 &
-          sleep 1 # give xvfb time to start
+          Xvfb $DISPLAY -screen 0 800x600x24 -fbdir /var/tmp/ &
+          sleep 1; while [ ! -f /var/tmp/Xvfb_screen0 ]; do sleep 0.5; done # give xvfb time to start, even on slow CI runs
           v gret -r ~/code/doom -t ./doom-regression-images/vgret.doom.toml -v ./doom-sample_images ./doom-regression-images
 
       - name: Upload regression to imgur

.github/workflows/gg_regressions_ci.yml

@@ -43,8 +43,8 @@ jobs:
         id: compare
         continue-on-error: true
         run: |
-          Xvfb $DISPLAY -screen 0 1280x1024x24 &
-          sleep 1 # give xvfb time to start
+          Xvfb $DISPLAY -screen 0 1280x1024x24 -fbdir /var/tmp/ &
+          sleep 1; while [ ! -f /var/tmp/Xvfb_screen0 ]; do sleep 0.5; done # give xvfb time to start, even on slow CI runs
           ./v gret -t ./gg-regression-images/vgret.v_examples.toml -v ./gg-sample_images ./gg-regression-images
 
       - name: Upload regression to imgur