Fix include-what-you-use problem in android-pubkey.c.
This fixes a problem building against BoringSSL master.
Change-Id: Ib052c6a59454126a83e32e9a43391470aca7356a
diff --git a/libcrypto_utils/android_pubkey.c b/libcrypto_utils/android_pubkey.c
index 9cd9aab..3052e52 100644
--- a/libcrypto_utils/android_pubkey.c
+++ b/libcrypto_utils/android_pubkey.c
@@ -20,6 +20,8 @@
#include <stdlib.h>
#include <string.h>
+#include <openssl/bn.h>
+
// Better safe than sorry.
#if (ANDROID_PUBKEY_MODULUS_SIZE % 4) != 0
#error RSA modulus size must be multiple of the word size!