Since 2006, commit d270463e, _bfd_elf_copy_private_section_data has
copied over SHF_MASKOS and SHF_MASKPROC flags.  That makes the buggy
code in sh_elf64_copy_private_data_internal redundant.

bfd/
	PR 17755
	* elf64-sh64.c (sh_elf64_copy_private_data_internal): Delete code
	copying SHF_SH5_ISA32.
binutils/testsuite/
	* binutils-all/strip-11.d: New test.
	* binutils-all/objcopy.exp: Run it.