*printf-posix: Avoid test failures. Make tests work on MacOS X, Cygwin.

*printf-posix: Avoid test failures. Make tests work on MacOS X, Cygwin.

* tests/test-fprintf-posix3.c: Include "resource-ext.h".
(main): Perform test also when getrlimit and setrlimit don't exist or
when setrlimit of RLIMIT_DATA fails (like on Cygwin). Instead of
limiting the address space size using setrlimit, compare the address
space size before and after the the test.
* tests/test-dprintf-posix2.c: Likewise.
* tests/test-fprintf-posix3.sh: Update skip messages.
* tests/test-dprintf-posix2.sh: Likewise.
* modules/fprintf-posix-tests (Depends-on): Add get-rusage-as.
* modules/dprintf-posix-tests (Depends-on): Likewise.
Reported by Bruce Korb <bkorb@gnu.org> and
Gary V. Vaughan <gary@gnu.org>.