tests: don't require debug system() to pass

tests: don't require debug system() to pass

When running a cross-compilation to mingw on a Linux host,
but without a valid mingw rm executable, the debug-only
system() call would fail.  This is not fatal to the test,
since the call is merely a debugging aid if a prior call to
the test encountered a failure and left garbage; in general,
the tests should pass and the system() call have nothing to
clean in the first place.  Also, the system() call only
needs to happen once at startup, not once per iteration
into the tests performed by .h files.

* tests/test-lstat.h (test_lstat_func): Move debug cleanup...
* tests/test-rmdir.h (test_rmdir_func): Likewise.
* tests/test-unlink.h (test_unlink_func): Likewise.
* tests/test-fstatat.c (main): ...into callers.
* tests/test-lstat.c (main): Likewise.
* tests/test-rmdir.c (main): Likewise.
* tests/test-unlink.c (main): Likewise.
* tests/test-unlinkat.c (main): Likewise.
* tests/test-areadlink-with-size.c (main): Don't require a
debug-only system call to pass, aiding cross-testing to mingw.
* tests/test-areadlink.c (main): Likewise.
* tests/test-areadlinkat-with-size.c (main): Likewise.
* tests/test-areadlinkat.c (main): Likewise.
* tests/test-canonicalize-lgpl.c (main): Likewise.
* tests/test-canonicalize.c (main): Likewise.
* tests/test-chown.c (main): Likewise.
* tests/test-fchownat.c (main): Likewise.
* tests/test-lchown.c (main): Likewise.
* tests/test-fdutimensat.c (main): Likewise.
* tests/test-futimens.c (main): Likewise.
* tests/test-link.c (main): Likewise.
* tests/test-linkat.c (main): Likewise.
* tests/test-mkdir.c (main): Likewise.
* tests/test-mkdirat.c (main): Likewise.
* tests/test-mkfifo.c (main): Likewise.
* tests/test-mkfifoat.c (main): Likewise.
* tests/test-mknod.c (main): Likewise.
* tests/test-readlink.c (main): Likewise.
* tests/test-remove.c (main): Likewise.
* tests/test-rename.c (main): Likewise.
* tests/test-renameat.c (main): Likewise.
* tests/test-symlink.c (main): Likewise.
* tests/test-symlinkat.c (main): Likewise.
* tests/test-utimens.c (main): Likewise.
* tests/test-utimensat.c (main): Likewise.

Signed-off-by: Eric Blake <ebb9@byu.net>