OpenJDK 11: Merging in java.lang.Integer (parseUnsignedInt())

This is part of merging upstream changes from OpenJDK 11.28. This CL
adds new API parseUnsignedInt(CharSequence, int, int, int); and adds
corresponding unit tests.

This also adds another new API for java.lang.Long:
parseLong(CharSequence, int, int, int).

Also added unit tests for both APIs (and more missing tests).

Bug: 207841289
Test: atest CtsLibcoreOjTestCases:test.java.lang.\
            {Long.{ParsingTest,Unsigned},Integer.Unsigned}
Change-Id: I506a305cf56c09852342e64d75cac99d21c19159
8 files changed