allocators: split allocators and pagelocker

Pagelocker is only needed for secure (usually wallet) operations, so don't make
the zero-after-free allocator depend on it.

src/crypter.h

@@ -5,9 +5,9 @@
 #ifndef BITCOIN_CRYPTER_H
 #define BITCOIN_CRYPTER_H
 
-#include "allocators.h"
 #include "keystore.h"
 #include "serialize.h"
+#include "support/allocators/secure.h"
 
 class uint256;