Report endianness in output of {dwarf, obj}dump

For biendian targets like ARM and AArch64, it is useful to have the
output of the llvm-dwarfdump and llvm-objdump report the endianness
used when the object files were generated.

Patch by Charlie Turner.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218391 91177308-0d34-0410-b5e6-96231b3b80d8