gdb: Have allocate_target_description return a unique_ptr

gdb: Have allocate_target_description return a unique_ptr

Update allocate_target_description to return a target_desc_up, a
specialisation of unique_ptr.

This commit does not attempt to make use of the unique_ptr in the
best possible way, in almost all cases we immediately release the
pointer from within the unique_ptr and then continue as before.

There are a few places where it was easy to handle the unique_ptr, and
in these cases I've done that.

Everything under gdb/features/* is auto-regenerated.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* arch/aarch32.c (aarch32_create_target_description): Release
	unique_ptr returned from allocate_target_description.
	* arch/aarch64.c (aarch64_create_target_description): Likewise.
	* arch/amd64.c (amd64_create_target_description): Likewise.
	* arch/arc.c (arc_create_target_description): Likewise.
	* arch/arm.c (arm_create_target_description): Likewise.
	* arch/i386.c (i386_create_target_description): Likewise.
	* arch/riscv.c (riscv_create_target_description): Update return
	type.  Handle allocate_target_description returning a unique_ptr.
	(riscv_lookup_target_description): Update to handle unique_ptr.
	* arch/tic6x.c (tic6x_create_target_description): Release
	unique_ptr returned from allocate_target_description.
	* features/microblaze-with-stack-protect.c: Regenerate.
	* features/microblaze.c: Regenerate.
	* features/mips-dsp-linux.c: Regenerate.
	* features/mips-linux.c: Regenerate.
	* features/mips64-dsp-linux.c: Regenerate.
	* features/mips64-linux.c: Regenerate.
	* features/nds32.c: Regenerate.
	* features/nios2.c: Regenerate.
	* features/or1k.c: Regenerate.
	* features/rs6000/powerpc-32.c: Regenerate.
	* features/rs6000/powerpc-32l.c: Regenerate.
	* features/rs6000/powerpc-403.c: Regenerate.
	* features/rs6000/powerpc-403gc.c: Regenerate.
	* features/rs6000/powerpc-405.c: Regenerate.
	* features/rs6000/powerpc-505.c: Regenerate.
	* features/rs6000/powerpc-601.c: Regenerate.
	* features/rs6000/powerpc-602.c: Regenerate.
	* features/rs6000/powerpc-603.c: Regenerate.
	* features/rs6000/powerpc-604.c: Regenerate.
	* features/rs6000/powerpc-64.c: Regenerate.
	* features/rs6000/powerpc-64l.c: Regenerate.
	* features/rs6000/powerpc-7400.c: Regenerate.
	* features/rs6000/powerpc-750.c: Regenerate.
	* features/rs6000/powerpc-860.c: Regenerate.
	* features/rs6000/powerpc-altivec32.c: Regenerate.
	* features/rs6000/powerpc-altivec32l.c: Regenerate.
	* features/rs6000/powerpc-altivec64.c: Regenerate.
	* features/rs6000/powerpc-altivec64l.c: Regenerate.
	* features/rs6000/powerpc-e500.c: Regenerate.
	* features/rs6000/powerpc-e500l.c: Regenerate.
	* features/rs6000/powerpc-isa205-32l.c: Regenerate.
	* features/rs6000/powerpc-isa205-64l.c: Regenerate.
	* features/rs6000/powerpc-isa205-altivec32l.c: Regenerate.
	* features/rs6000/powerpc-isa205-altivec64l.c: Regenerate.
	* features/rs6000/powerpc-isa205-ppr-dscr-vsx32l.c: Regenerate.
	* features/rs6000/powerpc-isa205-ppr-dscr-vsx64l.c: Regenerate.
	* features/rs6000/powerpc-isa205-vsx32l.c: Regenerate.
	* features/rs6000/powerpc-isa205-vsx64l.c: Regenerate.
	* features/rs6000/powerpc-isa207-htm-vsx32l.c: Regenerate.
	* features/rs6000/powerpc-isa207-htm-vsx64l.c: Regenerate.
	* features/rs6000/powerpc-isa207-vsx32l.c: Regenerate.
	* features/rs6000/powerpc-isa207-vsx64l.c: Regenerate.
	* features/rs6000/powerpc-vsx32.c: Regenerate.
	* features/rs6000/powerpc-vsx32l.c: Regenerate.
	* features/rs6000/powerpc-vsx64.c: Regenerate.
	* features/rs6000/powerpc-vsx64l.c: Regenerate.
	* features/rs6000/rs6000.c: Regenerate.
	* features/rx.c: Regenerate.
	* features/s390-gs-linux64.c: Regenerate.
	* features/s390-linux32.c: Regenerate.
	* features/s390-linux32v1.c: Regenerate.
	* features/s390-linux32v2.c: Regenerate.
	* features/s390-linux64.c: Regenerate.
	* features/s390-linux64v1.c: Regenerate.
	* features/s390-linux64v2.c: Regenerate.
	* features/s390-te-linux64.c: Regenerate.
	* features/s390-tevx-linux64.c: Regenerate.
	* features/s390-vx-linux64.c: Regenerate.
	* features/s390x-gs-linux64.c: Regenerate.
	* features/s390x-linux64.c: Regenerate.
	* features/s390x-linux64v1.c: Regenerate.
	* features/s390x-linux64v2.c: Regenerate.
	* features/s390x-te-linux64.c: Regenerate.
	* features/s390x-tevx-linux64.c: Regenerate.
	* features/s390x-vx-linux64.c: Regenerate.
	* mips-tdep.c (_initialize_mips_tdep): Release unique_ptr returned
	from allocate_target_description.
	* target-descriptions.c (allocate_target_description): Update
	return type.
	(print_c_tdesc::visit_pre): Release unique_ptr returned from
	allocate_target_description.

gdbserver/ChangeLog:

	* linux-low.cc (linux_process_target::handle_extended_wait):
	Release the unique_ptr returned from allocate_target_description.
	* linux-riscv-low.cc (riscv_target::low_arch_setup): Likewise.
	* linux-x86-low.cc (tdesc_amd64_linux_no_xml): Change type.
	(tdesc_i386_linux_no_xml): Change type.
	(x86_linux_read_description): Borrow pointer from unique_ptr
	object.
	(x86_target::get_ipa_tdesc_idx): Likewise.
	(initialize_low_arch): Likewise.
	* tdesc.cc (allocate_target_description): Update return type.

gdbsupport/ChangeLog:

	* tdesc.h (allocate_target_description): Update return type.