Use arc4random_buf instead of rand on NetBSD

Avoid old implementation of rand returning numbers with cyclical lower bits. Allow tests to pass.

Signed-off-by: gufe44 <gu981@protonmail.com>
diff --git a/tests/src/random.c b/tests/src/random.c
index 3345f78..45748a9 100644
--- a/tests/src/random.c
+++ b/tests/src/random.c
@@ -32,7 +32,7 @@
                                unsigned char *output,
                                size_t len )
 {
-#if !defined(__OpenBSD__)
+#if !defined(__OpenBSD__) && !defined(__NetBSD__)
     size_t i;
 
     if( rng_state != NULL )
@@ -45,7 +45,7 @@
         rng_state = NULL;
 
     arc4random_buf( output, len );
-#endif /* !OpenBSD */
+#endif /* !OpenBSD && !NetBSD */
 
     return( 0 );
 }