Drop default locale currency special case for euro

The condition mentioned in the comment no longer applies.
All European locales on Windows (MingW64) properly present EUR
as currency these days

libgnucash/app-utils/gnc-ui-util.c

@@ -51,7 +51,6 @@
 #include "Transaction.h"
 #include "gnc-engine.h"
 #include "gnc-features.h"
-#include "gnc-euro.h"
 #include "gnc-hooks.h"
 #include "gnc-locale-tax.h"
 #include "gnc-session.h"
@@ -1188,13 +1187,6 @@ gnc_locale_default_currency_nodefault (void)
 
     currency = gnc_commodity_table_lookup (table, GNC_COMMODITY_NS_CURRENCY, code);
 
-    /* Some very old locales (notably on win32) still announce a euro
-       currency as default, although it has been replaced by EUR in
-       2001. We use EUR as default in that case, but the user can always
-       override from gsettings. */
-    if (gnc_is_euro_currency (currency))
-        currency = gnc_get_euro();
-
     return (currency ? currency : NULL);
 }