Enable apps to get a UI_METHOD for the default prompter

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2204)
diff --git a/apps/apps.c b/apps/apps.c
index d911c0f..969b6b8 100644
--- a/apps/apps.c
+++ b/apps/apps.c
@@ -245,6 +245,11 @@
         ui_method = NULL;
     }
 }
+
+const UI_METHOD *get_ui_method(void)
+{
+    return ui_method;
+}
 #endif
 
 int password_callback(char *buf, int bufsiz, int verify, PW_CB_DATA *cb_tmp)