Add a space after node ID (upon --gen-ids).

There is often a space missing after the node ID in the generated code, e.g.:

  /* 889339*/ ret = type_tmp;

This space disappeared due to 23311c03 aka r20461, which commit
was unrelated:

before:     info->cStatements.push_back("/* " + numToString(stmt->id) + "*/ ");
after:     fprintf(outfile, "/* %7d */ ", stmt->id);

I am restoring this space for convenience highlighting in emacs
and for consistency.