binutils: readelf: support CTF dicts with non-native-endian symtabs

Now we have a way to tell libctf what the endianness of the symtab is,
get readelf to use it.  (objdump doesn't need to do so, nor does ld,
because they both use BFD-aware mechanisms to open CTF dicts, so libctf
can automatically figure the symtab endianness out.)

binutils/ChangeLog
2020-11-23  Nick Alcock  <nick.alcock@oracle.com>

	* readelf.c (dump_section_as_ctf): Call ctf_arc_symsect_endianness.