Fix NPE and wrong behavior of Typeface.isSupportedAxes

The Typeface kept by Paint object can be null if nobody calls
setTypeface. The null typeface is equivalent to the Typeface.DEFAULT.
To check whether the passed axis is usable for Typeface.DEFAULT, we
need to pass Typeface.DEFAULT to isSupportedAxes if no typeface was set
on the Paint.

At the same time this CL fixes an issue in isSupportedAxes.
If the requested axis is listed in the first element of axes list,
isSupportedAxes returned false due to wrong handling of binarySearch
result.

Bug: 62146672
Bug: 62147012
Test: am instrument -w -e class android.graphics.cts.PaintTest
android.graphics.cts/android.support.test.runner.AndroidJUnitRunner

Change-Id: I7c154adfe8a19d6ed24ad645df7c10cee7880461