Add check script for upstream rebase

rebase-check.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+msg=$(git log -1 --pretty=%s)
+case "$msg" in
+  "Update: Translations from eints"*)
+    echo "⏩ Skipping build for translation commit"
+    ;;
+  *)
+    cd build && ninja -j 20 openttd
+    ;;
+esac
+
+# cd build && make -j 10