regex: avoid warning when pointers are not long * lib/regcomp.c (parse_dup_op, mark_opt_subexp): Cast between void * and uintptr_t, not long, for portability to hosts where pointers and long have different sizes. Issue noted by Daniel P. Berrange in <http://lists.gnu.org/archive/html/bug-gnulib/2012-06/msg00122.html> and fix suggested by Bruno Haible in <http://lists.gnu.org/archive/html/bug-gnulib/2012-06/msg00128.html>.