Do not try to get the application value of the stolen register on the jump barrier used for drreg parity in filtered drcachesim instrumentation.
Enable thread filtering on non-x86: there is no missing support there.
Tested by locally enabling the tool.drcacheoff.burst_threadfilter test (it is disabled for AArch64 because of the #2007 (closed) link failure in some toolchains), working around #4468 (closed) with "-steal_register 25", and confirming that the drreg failure disappears with the fix here.
This is needed for the forthcoming new global filter for drcachesim (#4462 (closed)), in addition to the thread filter feature. An enabled-on-AArch64 test should be added as part of that feature to serve as a regression test here, if #2007 (closed) has not been resolved by then to enable the thread filter test.
Issue: #4461 (closed), #4462 (closed) Fixes #4461 (closed)