debugserver isn't saving and restoring the SVE/SME register state around
inferior function calls.
Making arbitrary function calls while in Streaming SVE mode is generally
a poor idea because a NEON instruction can be hit and crash the
expression execution, which is how I missed this, but they should be
handled correctly if the user knows it is safe to do.
Re-landing this change after fixing an incorrect behavior on systems
without SME support.
rdar://146886210
f1c6612202