Log Message:
bonnie++: assume large file support exists on NetBSD, handle
fallout from it.

NetBSD has large file support without O_LARGEFILE/open64/lseek64.
Not tested on other operating systems, but hopefully a non-functional
change for them.

This is the equivalent of removing the checks for large file support
and using O_LARGEFILE to test for the availability of different functions
for 64bit.