ASSERT skip_pc != NULL && cti_pc != NULL on AArch64

Running a proprietary app on AArch64 hits this assert about 20% of the time. Sometimes it's preceded by this "Not tested" but not always so I do not think there's a correlation.

It was run with these options:

bin64/drrun -debug -no_enable_reset -disable_traces -vm_size 2G -msgbox_mask 0 -stderr_mask 15 -- 

The assert:

<Not tested @core/unix/signal.c:4016>
...
<Application xxx (nnn).  Internal Error: DynamoRIO debug check failure: core/arch/mangle_shared.c:730 skip_pc != NULL && cti_pc != NULL
(Error occurred @181643 frags)
version 7.91.18368, custom build
-no_dynamic_options -code_api -stderr_mask 15 -stack_size 64K -signal_stack_size 64K -max_elide_jmp 0 -max_elide_call 0 -vmm_block_size 64K -initial_heap_unit_size 192K -initial_heap_nonpers_size 192K -initial_global_heap_unit_size 192K -heap_commit_increment 64K -cache_commit_increment 64K -vm_size 2097152K -early_injec