Add dummy |RAND_get_rand_method|.

Change-Id: I84b9a7606aaf28e582c79ada47df95b46ff2c2c2
Reviewed-on: https://boringssl-review.googlesource.com/18624
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

crypto/rand_extra/rand_extra.c

@@ -63,6 +63,8 @@ RAND_METHOD *RAND_SSLeay(void) {
   return (RAND_METHOD*) &kSSLeayMethod;
 }
 
+const RAND_METHOD *RAND_get_rand_method(void) { return RAND_SSLeay(); }
+
 void RAND_set_rand_method(const RAND_METHOD *method) {}
 
 void RAND_cleanup(void) {}

include/openssl/rand.h

@@ -111,6 +111,9 @@ struct rand_meth_st {
 /* RAND_SSLeay returns a pointer to a dummy |RAND_METHOD|. */
 OPENSSL_EXPORT RAND_METHOD *RAND_SSLeay(void);
 
+/* RAND_get_rand_method returns |RAND_SSLeay()|. */
+OPENSSL_EXPORT const RAND_METHOD *RAND_get_rand_method(void);
+
 /* RAND_set_rand_method does nothing. */
 OPENSSL_EXPORT void RAND_set_rand_method(const RAND_METHOD *);