fix crash for fdo#58306 by avoiding literal assign

OUStringBuffer doesn't handler append ( if it had been previously assigned to "" literal )

Change-Id: Ief4379490a4873fbee4117db5833111943b86334

basic/source/runtime/step0.cxx

@@ -1171,7 +1171,7 @@ void SbiRuntime::StepARGV()
 // is removed afterwards.
 void SbiRuntime::StepINPUT()
 {
-    OUStringBuffer sin = "";
+    OUStringBuffer sin;
     OUString s;
     char ch = 0;
     SbError err;