Use ro.build.version.known_codenames sysprop for KNOWN_CODENAMES.

The sysprop is needed to avoid JNI when accessing KNOWN_CODENAMES
from native code.

Bug: 211747008
Test:  atest android.os.cts.BuildTest#testBuildCodenameConstants
Change-Id: I713a122655f5f8a6a2fed5cee61bbe4094acbeb8
1 file changed