patch 9.0.1594: some internal error messages are translated

Problem:    Some internal error messages are translated.
Solution:   Consistently do not translate internal error messages.
            (closes #12459)
diff --git a/src/optionstr.c b/src/optionstr.c
index cfbcf3a..fa7084c 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -379,7 +379,7 @@
 	if (idx < 0)	// not found (should not happen)
 	{
 	    semsg(_(e_internal_error_str), "set_string_option_direct()");
-	    siemsg(_("For option %s"), name);
+	    siemsg("For option %s", name);
 	    return;
 	}
     }