Rename nativeHoldsLock to holdsLock and make it work on current thread

The Java native method nativeHoldsLock has been renamed to match the
upstream OpenJDK 8u121-b13 and changed from an instance method on Thread
to a static method.

This makes the corresponding change to the native implementation of that
method.

Test: make checkbuild, flash, CtsLibcoreTestCases
Bug: 74379469
Change-Id: Ib9dedccd3014c01c148ff824764be319c2a7a123