libctf: do not print array declarators backwards

The CTF declarator stack code (used by ctf_type_aname() and thus
ultimately by ctf-dump.c and objdump --ctf etc) contains careful
code to prepend array declarators to the stack it's building up
on the grounds that array declarators are ordered inside out: only
they're not, they're ordered outside in.

This has led to our (non-upstreamed) compiler emitting array declarators
backwards for years, because it looks backwards in the dumper unless
it's actually emitted backwards into the CTF so the dumper can wrongly
reverse it again: but

  int[5][6]

should be an array of 6 int[5]s, not an array of 5 int[6]'s, so even if
the dumper gets it right, actual users calling ctf_array_info are going
to see a completely wrong type graph with the wrong bounds in it.

Fix trivial.

libctf/ChangeLog
2021-01-05  Nick Alcock  <nick.alcock@oracle.com>

	* ctf-decl.c (ctf_decl_push): Don't print array decls backwards.