frameworks/base: switch to using NativeConstants.

NativeCrypto is a conscrypt class that contained several OpenSSL
constants. NativeConstants is the new class that contains the same
thing, but the latter is automatically generated and thus won't drift
from the C headers.

Bug: 20521989

Change-Id: I45c7b9a6844a06e3ffd09be692ebf733e1ebbbcc
diff --git a/tools/obbtool/pbkdf2gen.cpp b/tools/obbtool/pbkdf2gen.cpp
index 98d67c0..f1d8d04 100644
--- a/tools/obbtool/pbkdf2gen.cpp
+++ b/tools/obbtool/pbkdf2gen.cpp
@@ -20,6 +20,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>