cgroup-rstat-flushing: include errno.h issues

The build check bots cannot handle include of errno.h.
Trying different approaches.

Signed-off-by: Jesper Dangaard Brouer <[email protected]>

examples/cgroup-rstat-flushing.bpf.c

@@ -10,7 +10,7 @@
 #include <vmlinux.h>
 #include <bpf/bpf_tracing.h>
 #include "maps.bpf.h"
-#include "errno.h"
+#include <errno.h>
 
 #define MAX_CGROUP_LEVELS 5