Generic/AbstractClassNamePrefix: fix up incorrect code comment

This sniff only listens to `T_CLASS`. It does not listen to
`T_ANON_CLASS`. So the removed code comment is incorrect. The if
condition is still valid to bail early when live coding, but it does not
ever apply to anonymous classes.

Author: rodrigoprimo

src/Standards/Generic/Sniffs/NamingConventions/AbstractClassNamePrefixSniff.php

@@ -45,7 +45,7 @@ public function process(File $phpcsFile, $stackPtr)
 
         $className = $phpcsFile->getDeclarationName($stackPtr);
         if ($className === null) {
-            // We are not interested in anonymous classes.
+            // Live coding or parse error.
             return;
         }