* (print_ascii, dump_strings): Check for isascii before isprint.

* (print_ascii, dump_strings): Check for isascii before isprint.
(dump_strings): Free malloc'd buffer before returning.
(skip): Return non-zero if an error occurred, zero otherwise.
Exit only if asked to skip beyond end of combined input.
(check_and_close): New function.
(skip, read_block, read_char): Call check_and_close when done
processing the file associated with in_stream.
(skip, read_block, read_char): Set have_read_stdin.
(main): Close stdin (if it was ever read) and check for errors
just before exiting.
(write_block, dump_strings, dump): Don't test return value from
functions that operate on streams.  Rely on later ferror tests.