Option -hw_cache_consistency not working on AArch64

If you run the program from #2055 with a debug build of a2beedcca0772ac28bb978e56e35e02d2461182c you get:

`Internal Error: DynamoRIO debug check failure: /home/egrimley/dr-upstream/dynamorio/core/unix/signal.c:4118 get_sigcxt_stolen_reg(sc) != (reg_t)*get_dr_tls_base_addr()`

The same happens (with a different line number) with `release_8.0.0-1`, `release_9.0.1` or `release_10.0.0` so the option has perhaps never worked on AArch64.