Route error logs to the kernel during early boot.

This is needed to debug vold mounting errors before adb is up. It also
helps diagnose failures on devices that store dmesg persistently.

Tested by adding an error log with serial attached.

Bug: 205314634
Test: manual test
Change-Id: Ia095340c562e3f1f94bc44c5d13ad466a7a35345
1 file changed