elf: Keep only one '@' for undefined versioned symbols

elf: Keep only one '@' for undefined versioned symbols

The symbol string table in the .symtab section is optional and cosmetic.
Keep only one '@' for undefined versioned symbols, which are defined in
shared objects, in the symbol string table.  Update "nm -D" to display
only one '@' for undefined versioned symbols.

bfd/

	PR ld/26382
	* elflink.c (elf_link_output_symstrtab): Keep only one '@' for
	versioned symbols, which are defined in shared objects, in
	symbol string table.

binutils/

	PR ld/26382
	* nm.c (print_symname): Display only one '@' for undefined
	versioned symbols.
	* doc/binutils.texi: Update nm version information.

ld/

	PR ld/26382
	* testsuite/ld-elf/pr26302.nd: Updated.
	* testsuite/ld-elf/pr26302.rd: New file.
	* testsuite/ld-elf/shared.exp: Add a test for readelf -sW.