simpleperf: add test for a kernel bug making zero dyn_size.

Also fix a tiny problem in support_mmap2 test.

Bug: 22612370
Test: run simpleperf_unit_test, it successes on walleye,
Test: and fails on bullhead (which has 3.10 kernel).
Change-Id: I1af69a05446ddb61af6c24b34dc689afac8ee71d
1 file changed