pgo: full-headless-cage: new headless variant

Appears to work, but cage spams a lot of

 00:00:08.026 [types/wlr_output.c:720] Basic output test failed for HEADLESS-1
 00:00:08.036 [types/wlr_output.c:720] Basic output test failed for HEADLESS-1

pgo/full-headless-cage.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -eu
+
+srcdir=$(realpath "${1}")
+blddir=$(realpath "${2}")
+
+runtime_dir=$(mktemp -d)
+trap "rm -rf '${runtime_dir}'" EXIT INT HUP TERM
+
+# Run Sway. full-headless-sway-inner.sh ends with a ‘swaymsg exit’
+XDG_RUNTIME_DIR="${runtime_dir}" WLR_BACKENDS=headless cage "${srcdir}"/pgo/full-inner.sh "${srcdir}" "${blddir}"
+
+# Cage’s exit code doesn’t reflect our script’s exit code
+[ -f "${blddir}"/pgo-ok ] || exit 1

pgo/pgo.sh

@@ -3,7 +3,7 @@
 set -eu
 
 usage_and_die() {
-    echo "Usage: ${0} none|partial|full-current-session|full-headless-sway|[auto] <source-dir> <build-dir> [meson options]"
+    echo "Usage: ${0} none|partial|full-current-session|full-headless-sway|full-headless-cage|[auto] <source-dir> <build-dir> [meson options]"
     exit 1
 }
 
@@ -41,7 +41,7 @@ case $(${CC-cc} --version) in
 esac
 
 case ${mode} in
-    partial|full-current-session|full-headless-sway)
+    partial|full-current-session|full-headless-sway|full-headless-cage)
     ;;
 
     none)
@@ -56,6 +56,8 @@ case ${mode} in
             mode=full-current-session
         elif command -v sway > /dev/null; then
             mode=full-headless-sway
+        elif command -v cage > /dev/null; then
+            mode=full-headless-cage
         else
             mode=partial
         fi