Fix TestDataFormatterScript for Linux.

[chaoren]

Summary

m_function_name will contain a dummy name for the auto-generated function from
the python script on Linux. Check for script name first.

[granata.enrico]

That seems reasonable, yes.

In general, I wish I had done this not via two strings - only one of which gets to be valid in some arbitrary order - but via either two distinct subclasses, or at least via a pair of a string and an enum class specifying the kind.

But that is clearly beyond the scope of you fixing this test case. Your change is fine.

lldb/trunk/source/DataFormatters/TypeSummary.cpp

ScriptSummaryFormat::GetDescription ()
     StreamString sstr;
     sstr.Printf ("%s%s%s%s%s%s%s\n  ",       Cascades() ? "" : " (not cascading)",
                  !DoesPrintChildren(nullptr) ? "" : " (show children)",
                  !DoesPrintValue(nullptr) ? " (hide value)" : "",
                  IsOneLiner() ? " (one-line printout)" : "",
                  SkipsPointers() ? " (skip pointers)" : "",
                  SkipsReferences() ? " (skip references)" : "",
                  HideNames(nullptr) ? " (hide member names)" : "");
-    if (m_function_name.empty())
-    {
-        if (m_python_script.empty())
-        {
+        if (m_function_name.empty())
+        {
             sstr.PutCString("no backing script");
         }
         else
         {
-            sstr.PutCString(m_python_script.c_str());
+            sstr.PutCString(m_function_name.c_str());
         }
     }
     else
     {
-        sstr.PutCString(m_function_name.c_str());
+        sstr.PutCString(m_python_script.c_str());
     }
     return sstr.GetString();
-    
 }