[ELF] Allow misaligned SHT_GNU_verneed

Bazel created interface shared objects (.ifso) may be misaligned.  We use
llvm::support::detail::packed_endian_specific_integral under the hood
which allows reading of misaligned values, so there is not a need to
diagnose (in LLD we don't intend to support sophisticated parsing for
SHT_GNU_*).