Don't make generated files read-only. That would bother too many

Don't make generated files read-only.  That would bother too many
people.  However, do retain the ability to work when targets are
read-only: remove the destination and temporary files before writing
them (when generated via sed or echo), or by using the -f option for
both cp and mv commands.  Suggestion to use -f from Paul Eggert.
* modules/alloca-opt, modules/argz, modules/arpa_inet:
* modules/byteswap, modules/configmake, modules/fcntl:
* modules/fnmatch, modules/getopt, modules/glob, modules/inttypes:
* modules/localcharset, modules/netinet_in, modules/poll:
* modules/stdbool, modules/stdint, modules/sys_select:
* modules/sys_socket, modules/sys_stat, modules/sysexits: