APP CRASH: drcachesim delayed tracing broken on 32-bit ARM

Commit 72275ad4 for #4496 (closed) via PR #4507 broke ARM delayed tracing:

$ bin32/drrun -t drcachesim -trace_after_instrs 20000 -- suite/tests/bin/simple_app
...
Hit delay threshold: enabling tracing.
<Application tried to execute from unreadable memory 0xb71db0a2.
This may be a result of an unsuccessful attack or a potential application vulnerability.>
<Application /home/derek/dr/git/build_dbg_tests/suite/tests/bin/simple_app (1075).  Application exception at PC 0xb71db0a2.  
Signal 11 delivered to application as default action.
Callstack:
	0xb71db0a2  
	0x0001e916  
	0x00000000  
>

It's due to an incorrect ISA mode on the dr_redirect_execution from the new synchall flush.