Move RunningTees singleton to cpp file.

If the singleton is in the header file, the fast mixers will get a
different instance from audio flinger. That will result in not able to
dump from fast mixers.

Bug: 329301856
Test: dump wav file
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:ad945932ed39b6249a681f16e12d7ea1e5e1d213)
Merged-In: Ic067f36efd84bd4f1da566b7db673c9a33bf5141
Change-Id: Ic067f36efd84bd4f1da566b7db673c9a33bf5141
2 files changed