[PATCH] nm: Add --quiet to suppress "no symbols" diagnostic

[Fangrui Song]

On 2021-02-12, Fangrui Song via Binutils wrote:
>	PR binutils/27408
>	* readelf.c (quiet): New option flag.
>	(display_rel_file): If quiet is enabled, suppress "no symbols".
>	(enum long_option_values): New enum to hold long option value.
>	(options): Add quiet.
>	(main): Handle the new option.
>	* NEWS: Mention the new feature.
>	* docs/binutils.texi: Document the new feature.

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