bpf: Fix build error in case of !CONFIG_DEBUG_INFO_BTF

BTF_ID_FLAGS macro needs to be able to take 0 or 1 args, so make it a
variable argument. BTF_SET8_END is incorrect, it should just be empty.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: ab21d606 ("bpf: Introduce 8-byte BTF set")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220722113605.6513-1-memxor@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/btf_ids.h

@@ -206,7 +206,7 @@ extern struct btf_id_set8 name;
 
 #define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
 #define BTF_ID(prefix, name)
-#define BTF_ID_FLAGS(prefix, name, flags)
+#define BTF_ID_FLAGS(prefix, name, ...)
 #define BTF_ID_UNUSED
 #define BTF_ID_LIST_GLOBAL(name, n) u32 __maybe_unused name[n];
 #define BTF_ID_LIST_SINGLE(name, prefix, typename) static u32 __maybe_unused name[1];
@@ -215,7 +215,7 @@ extern struct btf_id_set8 name;
 #define BTF_SET_START_GLOBAL(name) static struct btf_id_set __maybe_unused name = { 0 };
 #define BTF_SET_END(name)
 #define BTF_SET8_START(name) static struct btf_id_set8 __maybe_unused name = { 0 };
-#define BTF_SET8_END(name) static struct btf_id_set8 __maybe_unused name = { 0 };
+#define BTF_SET8_END(name)
 
 #endif /* CONFIG_DEBUG_INFO_BTF */