Add the -u option to support running on USER builds

Because USER builds do not have root access, the new -u
option modifies the script to create a 512 Mbyte file
in /data/local/tmp/testfile, and use that for testing.
Read tests are disabled (because the inability to drop
the caches makes them pointless), and the write tests
now go through the filesystem layer, so it is not fair
to compare these results to a non-userbuild run.  However,
this test can help with before/after tests to see if
a change has improved the I/O performance of the system.

Change-Id: Id724f12e4564af7ced858de1df7c2d45b0a440b6
1 file changed