bpf: Always emit .BTF.ext section if generating BTF

bpf: Always emit .BTF.ext section if generating BTF

BPF applications, when generating BTF information should always create a
.BTF.ext section.
Current implementation was only creating it when -mco-re option was used.
This patch makes .BTF.ext always be generated for BPF target objects.
The patch also adds conditions around btf_finalize function call
such that BTF deallocation happens later for BPF target.
For BPF, btf_finalize is only called after .BTF.ext is generated.

gcc/ChangeLog:

	* config/bpf/bpf.cc (bpf_option_override): Make .BTF.ext
	enabled by default for BPF.
	(bpf_file_end): Call BTF deallocation.
	(bpf_asm_init_sections): Correct condition.
	* dwarf2ctf.cc (ctf_debug_finalize): Conditionally execute BTF
	deallocation.
	(ctf_debuf_finish): Correct condition for calling
	ctf_debug_finalize.