libbpf: Sync in latest libbpf sources

Get latest changes and fixes for libbpf. Most importantly it pulls in
enum fwd resolution in btf_dedup().

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/lib/bpf b/lib/bpf
index cb658e9..27a5f60 160000
--- a/lib/bpf
+++ b/lib/bpf
@@ -1 +1 @@
-Subproject commit cb658e9724e3c34973eee913b1ff0cb9c50b8e53
+Subproject commit 27a5f60a8b6bcb2d460ac03772ae387eba36f2b6