simpleperf: show recording time before post processing.

Sometimes post processing can take a lot of time (like when
--post-unwind=yes is used). This can cause confusion about the recording
time. So add a log to show recording time before post processing.

Also display time in seconds instead of milliseconds, to be consistent
with --duration.

Bug: 188536575
Test: run simpleperf_unit_test.
Test: run simpleperf manually.
Change-Id: I705030201ed72d82a76e8ed91f9cc517dfd20d25
1 file changed