bpf: Fix access string default for CO-RE type based relocations

Although part of all CO-RE relocation data, type based relocations do
not require an access string.
Initial implementation defined it as an empty string.
On the other hand, libbpf when parsing the CO-RE relocations verifies
that those strings would contain "0", otherwise reports an error.
This patch makes GCC compliant with libbpf expectations.

gcc/Changelog:
	* config/bpf/btfext-out.cc (cpf_core_reloc_add): Correct for new code.
	Add assert to validate the string is set.
	* config/bpf/core-builtins.cc (cr_final): Make string struct
	field as const.
	(process_enum_value): Correct for field type change.
	(process_type): Set access string to "0".

gcc/testsuite/ChangeLog:
	* gcc.target/bpf/core-builtin-type-based.c: Correct.
	* gcc.target/bpf/core-builtin-type-id.c: Correct.

0 files changed, 0 insertions, 0 deletions