devel/android-tools-{adb,fastboot}: update to 8.1.0.r2

Changes: https://android.googlesource.com/platform/system/core/+log/android-8.0.0_r24..android-8.1.0_r2/adb
Changes: https://android.googlesource.com/platform/system/core/+log/android-8.0.0_r24..android-8.1.0_r2/fastboot