t1200: work around a bug in some implementations of "find"
"find path ..." command should exit with zero status only when all path
operands were traversed successfully. When a non-existent path is given,
however, some implementations of "find" (e.g. OpenBSD 4.6) exit with zero
status and break the last test in t1200.
Rewrite the test to check that there is no regular files in the objects
fan-out directories to work around this bug; it is closer to what we are
testing anyway.
Signed-off-by: Junio C Hamano <gitster@pobox.com>