libbpf: update to latest upstream version

This brings in KERNEL_VERSION macro fix, among few other recent features.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
diff --git a/src/cc/libbpf b/src/cc/libbpf
index ea5752c..174d0b7 160000
--- a/src/cc/libbpf
+++ b/src/cc/libbpf
@@ -1 +1 @@
-Subproject commit ea5752c64183fa890ce15ce70e0eaabfbf437fe8
+Subproject commit 174d0b7b499fd90cb1d67bee689fb55974009f3e