simpleperf: check dump stack size and adjust its default value.

Improve error message by checking if dump stack size > 65528.
And adjust the default dump stack size to 65528, because I
find that it is the value I always want to use.

Bug: 29574526
Change-Id: I8f16dcf3a86a477f17d81fd387bf4dfa0dc0b341
Test: run simpleperf_unit_test.
2 files changed