[clang] [clang][SSAF] Allow no Data for summary analysis (PR #211342)

[Balázs Benics via cfe-commits]

================
@@ -15,13 +15,13 @@
 // UNKNOWN: no analysis registered for 'AnalysisName(NoSuchAnalysis)'
 
 // ============================================================================
-// Error: valid analysis name but LUSummary lacks entity data for it
+// Success: Analyese might not add summaries in every run.
----------------
steakhal wrote:

```suggestion
// Success: Analyses might not add summaries in every run.
```

https://github.com/llvm/llvm-project/pull/211342