Modify xfstests' fsx program for use in CrashMonkey

[ashmrtn]

xfstests in kdave's repo has a source file for a program called fsx that is meant to perform random write/truncate/allocate operations on a single file in the file system. This would be a useful tool for the CrashMonkey team because it would allow us to quickly bootstrap random tests.

The fsx program has a few extra things the CrashMonkey team may not need.

1. it creates 2 extra files in addition to the file used for testing. The purpose of these file should be investigated and they should not be created by fsx if they are not needed or should be created somewhere other than on the file system under test if they are useful.
2. fsx has an algorithm to generate data, but I do not know if it generates data the CrashMonkey team can easily check for if given an offset in a file. Part of CrashMonkey's tests include checks for proper data in files, so we would like to make sure that we know what data is being written to a file where. If needed, the fsx algorithm to create data to write to a file should be modified so that it writes data CrashMonkey can easily verify.