Online banking: Usage of gnucash registration key is available in more aqbanking versions.

To be precise, it is in aqbanking-5.7.8-git-1 and to-be-released
aqbanking-5.7.9 as well as aqbanking-5.99.24-git-1 and
to-be-released aqbanking-5.99.25. As it is needed mid-September 2019
for all bank users in Germany, we better make it available for both branches.

gnucash/import-export/aqb/gnc-ab-utils.c

@@ -159,13 +159,16 @@ gnc_AB_BANKING_new(void)
         api = AB_Banking_new("gnucash", NULL, 0);
         g_return_val_if_fail(api, NULL);
 
-#if AQBANKING_VERSION_INT >= 59925
+#if AQBANKING_VERSION_INT >= 59925 \
+    || (AQBANKING_VERSION_INT == 59924 && AQBANKING_VERSION_BUILD >= 1) \
+    || (AQBANKING_VERSION_INT >= 50709 && AQBANKING_VERSION_INT < 59900) \
+    || (AQBANKING_VERSION_INT == 50708 && AQBANKING_VERSION_BUILD >= 1)
         /* These two values must be set because newest bank regulation requires
         the bank servers to require it. The string itself results from our
         registration with the German bank association at
         https://www.hbci-zka.de/register/prod_register.htm (where the
         registration was requested and is managed by cstim). The function call was
-        introduced in aqbanking-5.99.25. */
+        introduced in aqbanking-5.99.25 and aqbanking-5.7.9. */
         AB_Banking_RuntimeConfig_SetCharValue(api, "fintsRegistrationKey", "412748A1836CDD07181CE1910");
         AB_Banking_RuntimeConfig_SetCharValue(api, "fintsApplicationVersionString", PACKAGE_VERSION);
 #endif