simpleperf: use libbacktrace_offline static library.

Device may not have libbacktrace_offline shared library, so always
using libbacktrace_offline static library.
Use simpleperf namespace to avoid conflicts with ThreadEntry in
libbacktrace.

Bug: 28152982
Change-Id: Ia2cdbee3b28556c790ccd7b061a801ed96f9b97c
(cherry picked from commit 040f7b4c62ce49f0af0746640e94d415764262cd)
4 files changed