x86-64: Skip protected check on symbol defined by linker

Skip symbol defined by linker when checking copy reloc on protected
symbol.

bfd/

	PR ld/24276
	* elf64-x86-64.c (elf_x86_64_check_relocs): Skip symbol defined
	by linker when checking copy reloc on protected symbol.

ld/

	PR ld/24276
	* testsuite/ld-i386/i386.exp: Run PR ld/24276 test.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-i386/pr24276.dso: New file.
	* testsuite/ld-i386/pr24276.warn: Likewise.
	* testsuite/ld-x86-64/pr24276.dso: Likewise.
	* testsuite/ld-x86-64/pr24276.warn: Likewise.