Add libbpf_prog bpfRingbufProg.bpf target

This is a preparation for migrating to the Rust platform bpfloader.

Bug: 410982483
Test: m bpfRingbufProg.bpf bpfRingbufProg.o
Change-Id: I094635be14e56aac53384ac517538c2587367c44

include/defs/android_bpf_defs.h

@@ -18,6 +18,7 @@
 #define __always_inline __attribute__((__always_inline__))
 
 #include <linux/bpf.h>
+#include <sys/cdefs.h>
 
 #define DEFINE_BPF_MAP_BASE(the_map, TYPE, KeyType, ValueType, num_entries, gid)               \
     struct {                                                                                   \

progs/Android.bp

@@ -31,3 +31,11 @@ bpf {
     name: "bpfRingbufProg.o",
     srcs: ["bpfRingbufProg.c"],
 }
+
+libbpf_prog {
+    name: "bpfRingbufProg.bpf",
+    srcs: ["bpfRingbufProg.c"],
+    header_libs: [
+        "android_bpf_defs",
+    ],
+}

progs/bpfRingbufProg.c

@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
+// Because include_dirs is not allowed under system/bpf, include
+// <android_bpf_defs.h> only if the code is built for libbpf_prog target.
+#ifdef ENABLE_LIBBPF
+#include <android_bpf_defs.h>
+#else
 #include "bpf_helpers.h"
+#endif
 
 // This can't be easily changed since the program is loaded on boot and may be
 // run against tests at a slightly different version.