Adjust Checker assertion in 1004-checker-volatile-ref-load for heap poisoning.

The relative offset passed to the ADR instruction is usually
(i.e. when heap poisoning is disabled) 0xc (12 bytes), but it is 0x10
(16 bytes) when heap poisoning is enabled, as the emitted code
sequence includes a NEG instruction to unpoison the loaded reference.

(cherry picked from commit 40510ab49d6bb2bc65957aa72c00fbb371647f2d)

Test: art/test/testrunner/testrunner.py --target --64 -t 1004-checker-volatile-ref-load
      (with `ART_HEAP_POISONING` set to `true`)
Bug: 140507091
Bug: 36141117

Change-Id: I63c6c00abbe10dfcbbf88231f9f9995d3ba950fa