Enable native tracking for RS contexts to improve GC behavior.

This should prevent apps from leaking RS contexts as easily.

bug 18579193

Change-Id: I2d943ce4443ce7cb90ebdd3dd37d338eda6df3a2
Lose some unnecessary JNI from the zygote.

Bug: 18719692
Change-Id: Ie2d50400f10f3c54cfbf94e54656f6d704eac267
Merge "Lose some unnecessary JNI from the zygote."
Merge "Enable native tracking for RS contexts to improve GC behavior."