RootCanal: Use GD defaults to define OS_ANDROID

When OS_ANDROID is defined logs go to logcat.
When OS_ANDROID is not defined logs to stderr.

Bug: 157706301
Test: cert/run --host
Tag: #gd-refactor
Change-Id: I3e735a4716fbc35a3d66e03909fdbf905436d285
Merged-In: I3e735a4716fbc35a3d66e03909fdbf905436d285