Sync with latest libbpf repo

Sync with latest libbpf repo upto commit:
   94a49850c5ee Makefile: enforce gnu89 standard

Signed-off-by: Yonghong Song <yhs@fb.com>
diff --git a/introspection/bps.c b/introspection/bps.c
index 6ec02e6..232b23d 100644
--- a/introspection/bps.c
+++ b/introspection/bps.c
@@ -80,6 +80,7 @@
   [BPF_MAP_TYPE_RINGBUF] = "ringbuf",
   [BPF_MAP_TYPE_INODE_STORAGE] = "inode_storage",
   [BPF_MAP_TYPE_TASK_STORAGE] = "task_storage",
+  [BPF_MAP_TYPE_BLOOM_FILTER] = "bloom_filter",
 };
 
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))