Allow multiple native debug entries with same address.

We create packed entries which hold multiple methods and have
address aligned to 64k block that contains those methods.

If there is no method at the start of the block, it is possible
the new method will be JITed at that 64k-aligned address.

Test: test.py -b -r -t 137
Bug: 121363337
Change-Id: I2561b207f99e91e03f4709df5f318879c884a829