samples/bpf: replace legacy map with the BTF-defined map

With libbpf 1.0 release, support for legacy BPF map declaration syntax
had been dropped. If you run a program using legacy BPF in the latest
libbpf, the following error will be output.

    libbpf: map 'lwt_len_hist_map' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
    libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead

This commit replaces legacy map with the BTF-defined map.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230115071613.125791-7-danieltimlee@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/lwt_len_hist_kern.c

@@ -16,23 +16,13 @@
 #include <uapi/linux/in.h>
 #include <bpf/bpf_helpers.h>
 
-struct bpf_elf_map {
-	__u32 type;
-	__u32 size_key;
-	__u32 size_value;
-	__u32 max_elem;
-	__u32 flags;
-	__u32 id;
-	__u32 pinning;
-};
-
-struct bpf_elf_map SEC("maps") lwt_len_hist_map = {
-	.type = BPF_MAP_TYPE_PERCPU_HASH,
-	.size_key = sizeof(__u64),
-	.size_value = sizeof(__u64),
-	.pinning = 2,
-	.max_elem = 1024,
-};
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
+	__type(key, u64);
+	__type(value, u64);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+	__uint(max_entries, 1024);
+} lwt_len_hist_map SEC(".maps");
 
 static unsigned int log2(unsigned int v)
 {

samples/bpf/test_cgrp2_tc_kern.c

@@ -19,24 +19,13 @@ struct eth_hdr {
 	unsigned short  h_proto;
 };
 
-#define PIN_GLOBAL_NS		2
-struct bpf_elf_map {
-	__u32 type;
-	__u32 size_key;
-	__u32 size_value;
-	__u32 max_elem;
-	__u32 flags;
-	__u32 id;
-	__u32 pinning;
-};
-
-struct bpf_elf_map SEC("maps") test_cgrp2_array_pin = {
-	.type		= BPF_MAP_TYPE_CGROUP_ARRAY,
-	.size_key	= sizeof(uint32_t),
-	.size_value	= sizeof(uint32_t),
-	.pinning	= PIN_GLOBAL_NS,
-	.max_elem	= 1,
-};
+struct {
+	__uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
+	__type(key, u32);
+	__type(value, u32);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+	__uint(max_entries, 1);
+} test_cgrp2_array_pin SEC(".maps");
 
 SEC("filter")
 int handle_egress(struct __sk_buff *skb)