Add declarations for Android compatibility funcs.

Some parts of Android can't be updated yet so this change adds
declarations (only) for some functions that will be stubbed in
Android-specific code. (That Android-specific code will live in the
Android repo, not the BoringSSL repo.)

Trying to use these functions outside of Android will result in a link
error.

Change-Id: Iaa9b956e6408d21cd8fc34d90d9c15657e429877
Reviewed-on: https://boringssl-review.googlesource.com/2760
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/bn.h b/include/openssl/bn.h
index 37a4bba..0631b8c 100644
--- a/include/openssl/bn.h
+++ b/include/openssl/bn.h
@@ -802,6 +802,15 @@
 #define BN_FLG_CONSTTIME 0x04
 
 
+/* Android compatibility section.
+ *
+ * These functions are declared, temporarily, for Android because
+ * wpa_supplicant will take a little time to sync with upstream. Outside of
+ * Android they'll have no definition. */
+
+OPENSSL_EXPORT BIGNUM *get_rfc3526_prime_1536(BIGNUM *bn);
+
+
 #if defined(__cplusplus)
 }  /* extern C */
 #endif