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/system_properties/contexts_serialized.cpp b/libc/system_properties/contexts_serialized.cpp
index 12e9715..6ccd46c 100644
--- a/libc/system_properties/contexts_serialized.cpp
+++ b/libc/system_properties/contexts_serialized.cpp
@@ -31,6 +31,7 @@
 #include <fcntl.h>
 #include <limits.h>
 #include <sys/mman.h>
+#include <sys/prctl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -38,7 +39,6 @@
 
 #include <async_safe/log.h>
 
-#include "private/bionic_prctl.h"
 #include "system_properties/system_properties.h"
 
 bool ContextsSerialized::InitializeContextNodes() {