Fix OOBR in `DisassemblerX86::DumpNops()`.

Test: SANITIZE_HOST=address ASAN_OPTIONS=detect_leaks=0 \
      m test-art-host-gtest
Bug: 334200225
Flag: EXEMPT bugfix
Change-Id: I90820419faecebe99f795b73c90b9adfbe93b8ed
2 files changed