overlay/016: split into two tests

overlay/016: split into two tests

overlay/016 tests two cases of ro/rw fd data inconsistecies -
one using pread and one using mmap read (i.e. mread).

The first case now passes with stacked overlay file operations
patch set merged. The second case will still fail.

By splitting the two test cases we get one regression test for
the common case of ro/rw fd data inconsistecy with pread and
one test to track the remaining non-standard behavior of
overlayfs w.r.t mmap.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>