Fix make fmt/lint not to fail when file is deleted (#3112)

Author: denik

tools/lintdiff.py

@@ -48,11 +48,11 @@ def main():
             d = os.path.dirname(filename)
             dirs.add(d)
 
+    dirs = ["./" + d for d in sorted(dirs) if os.path.exists(d)]
+
     if not dirs:
         sys.exit(0)
 
-    dirs = ["./" + d for d in sorted(dirs)]
-
     cmd = ["golangci-lint"] + args.args + dirs
     print("+ " + " ".join(cmd), file=sys.stderr, flush=True)
     os.execvp(cmd[0], cmd)