binutils, ld: make objdump --ctf's parameter optional

binutils, ld: make objdump --ctf's parameter optional

ld by default (and always, unless adjusted with a hand-rolled linker
script) emits deduplicated CTF into the .ctf section.  But viewing
it needs you to explicitly tell objdump this: it doesn't default
its argument, even though what you always end up typing is
--ctf=.ctf.

This is annoying, so make the argument optional.

binutils/ChangeLog
2021-10-25  Nick Alcock  <nick.alcock@oracle.com>

	* objdump.c (usage): --ctf now has an optional argument.
	(main): Adjust accordingly.
	(dump_ctf): Default it.
	* doc/ctf.options.texi: Adjust.

ld/ChangeLog
2021-10-25  Nick Alcock  <nick.alcock@oracle.com>

	* testsuite/ld-ctf/array.d: Change --ctf=.ctf to --ctf.
	* testsuite/ld-ctf/conflicting-cycle-1.B-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-1.B-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-1.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.A-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.A-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.C-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.C-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-enums.d: Likewise.
	* testsuite/ld-ctf/conflicting-typedefs.d: Likewise.
	* testsuite/ld-ctf/cross-tu-cyclic-conflicting.d: Likewise.
	* testsuite/ld-ctf/cross-tu-cyclic-nonconflicting.d: Likewise.
	* testsuite/ld-ctf/cross-tu-into-cycle.d: Likewise.
	* testsuite/ld-ctf/cross-tu-noncyclic.d: Likewise.
	* testsuite/ld-ctf/cycle-1.d: Likewise.
	* testsuite/ld-ctf/cycle-2.A.d: Likewise.
	* testsuite/ld-ctf/cycle-2.B.d: Likewise.
	* testsuite/ld-ctf/cycle-2.C.d: Likewise.
	* testsuite/ld-ctf/data-func-conflicted.d: Likewise.
	* testsuite/ld-ctf/diag-cttname-null.d: Likewise.
	* testsuite/ld-ctf/diag-cuname.d: Likewise.
	* testsuite/ld-ctf/diag-parlabel.d: Likewise.
	* testsuite/ld-ctf/enum-forward.d: Likewise.
	* testsuite/ld-ctf/enums.d: Likewise.
	* testsuite/ld-ctf/forward.d: Likewise.
	* testsuite/ld-ctf/function.d: Likewise.
	* testsuite/ld-ctf/nonrepresentable.d: Likewise.
	* testsuite/ld-ctf/slice.d: Likewise.
	* testsuite/ld-ctf/super-sub-cycles.d: Likewise.