Don't collect stats if they won't be used

When the encoder is run continuously for a few minutes at 60 fps, the
total_target_vs_actual field overflows. Since this field is a signed
integer that's considered undefined behavior in C++, which causes an
abort when used in an android binary (those run with ubsan enabled)

Bug: 154172422
Test: run cuttelfish with webrtc enabled for an hour
Change-Id: I8f7d9d0884311a6338bdcdec76348b8cc3ce8c69
1 file changed