du: don't infloop for --files0-from=DIR

du: don't infloop for --files0-from=DIR

* src/du.c (main): Fail on AI_ERR_READ error, rather than merely
diagnosing and continuing.  Based on a patch by Stefan Vargyas.
Also move the handling of AI_ERR_EOF into the case stmt.
Do not report ferror/fclose(stdin) failure when we've
already diagnosed e.g., failure to read the DIR, above.
Bug introduced by 2008-11-24 commit 031e2fb5, "du: read and
process --files0-from= input a name at a time,".
* src/wc.c: Handle read failure as with du: do not exit
immediately, but rather go on to print any total and to clean-up.
As above, move the handling of AI_ERR_EOF into the case stmt.
* tests/du/files0-from-dir: New file, to test both du and wc.
* tests/Makefile.am (TESTS): Add it.
* NEWS (Bug fixes): Mention it.