test: add framework for generic fake random number generator

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13652)
diff --git a/test/testutil.h b/test/testutil.h
index 491082c..93c91a4 100644
--- a/test/testutil.h
+++ b/test/testutil.h
@@ -566,6 +566,11 @@
 uint32_t test_random(void);
 void test_random_seed(uint32_t sd);
 
+/* Fake non-secure random number generator */
+OSSL_PROVIDER *fake_rand_start(OSSL_LIB_CTX *libctx);
+void fake_rand_finish(OSSL_PROVIDER *p);
+void fake_rand_set_callback(int (*cb)(unsigned char *out, size_t outlen));
+
 /* Create a file path from a directory and a filename */
 char *test_mk_file_path(const char *dir, const char *file);