test 194, test tricky mapping/conversion around holes

Related to
http://oss.sgi.com/bugzilla/show_bug.cgi?id=801

Latest patch posted on that bug makes this testcase pass...

first 2 tests are simple buffred writ tests making sure stale
data isn't exposed, and hole-blocks aren't mapped.

2nd 2 tests are more related to the above bug, tricky testcase
uncovered by fsx on ppc64 which actually re-maps a block
which should be a hole, bringing stale data back into existence.

V2, don't use non-posix awk extensions

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>