x86-64: Return SHN_COMMON on non-ELF input elf_x86_64_common_definition segfaults on PE/x86-64 input. Return SHN_COMMON on non-ELF input. Linker now gets assertion fail at bfd/coffgen.c:575, instead of getting segfault. PR ld/34449 * elf64-x86-64.c (elf_x86_64_common_definition): Return SHN_COMMON on non-ELF input. Signed-off-by: H.J. Lu <hjl.tools@gmail.com>