[Hexagon] ELF attributes for Hexagon (#85359)

Defines a subset of attributes and emits them to a section called
.hexagon.attributes.

The current attributes recorded are the attributes needed by

[Hexagon] ELF attributes for Hexagon (#85359)

Defines a subset of attributes and emits them to a section called
.hexagon.attributes.

The current attributes recorded are the attributes needed by
llvm-objdump to automatically determine target features and eliminate
the need to manually pass features.

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