OpenJDK 11: Merging in java.lang.Long (toUnsignedString0() helper)

This is part of merging upstream changes from OpenJDK 11.28. This CL
updates toUnsignedString0() helper method.

Bug: 207772338
Test: treehugger
Change-Id: I6496ecd4f4f18d41ca75419c0d29336703690246
1 file changed