Compact-unwind encodings are more limited than DWARF frame descriptions. For
functions whose frame layout cannot be described by a compact unwind encoding,
the encoding for the function will specify "use DWARF", and the corresponding
unwind-info record will use the low bits of the encoding to point to the FDE
for the function.
We test this with a frame-pointer=none function, since these frame layouts
always triger a fall-back to DWARF on arm64.
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