Add demangling support to readelf.

Add demangling support to readelf.

	PR binutils/26331
	* readelf.c (do_demangle): New option flag.
	(print_symbol): If do_demangle is enabled, demangle the symbol.
	(enum long_option_values): New enum to hold long option values.
	(options): Add demangle, no-demangle, recursion-limit and
	no-recursion-limit options.  Alpha sort the table.
	(usage): Describe the new options.
	(parse_args): Handle the new options.
	* NEWS: Mention the new feature.
	* doc/binutils.texi: Document the new feature.
	* testsuite/binutils-all/readelf.exp: Test the new feature.
	* testsuite/binutils-all/mangled.s: New file - assembler source.
	* testsuite/binutils-all/readelf.demangled: New file - expected
	output from readelf.