Add PR_SET_VMA and PR_SET_VMA_ANON_NAME to <sys/prctl.h>.

We've copied & pasted these to too many places. And if we're going to
have another go at upstreaming these, that's probably yet another reason
to have the *values* in just one place. (Even if upstream wants different
names, we'll likely keep the legacy names around for a while for source
compatibility.)

Bug: http://b/111903542
Test: ran tests
Change-Id: I8ccc557453d69530e5b74f865cbe0b458c84e3ba
diff --git a/libc/upstream-openbsd/android/include/arc4random.h b/libc/upstream-openbsd/android/include/arc4random.h
index afa8d14..5f0b15e 100644
--- a/libc/upstream-openbsd/android/include/arc4random.h
+++ b/libc/upstream-openbsd/android/include/arc4random.h
@@ -26,11 +26,10 @@
 #include <pthread.h>
 #include <signal.h>
 #include <sys/mman.h>
+#include <sys/prctl.h>
 
 #include <async_safe/log.h>
 
-#include "private/bionic_prctl.h"
-
 // Android gets these from "thread_private.h".
 #include "thread_private.h"
 //static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;