Move #if evaluation flag out of PersistentParserState

Move this flag onto the parser instead. Now the
only client of PersistentParserState is code
completion.

tools/SourceKit/lib/SwiftLang/SwiftEditor.cpp

@@ -715,7 +715,7 @@ public:
     Parser->getDiagnosticEngine().addConsumer(DiagConsumer);
 
     // Collecting syntactic information shouldn't evaluate # conditions.
-    Parser->getParser().State->PerformConditionEvaluation = false;
+    Parser->getParser().EvaluateConditionals = false;
 
     // If there is a syntax parsing cache, incremental syntax parsing is
     // performed and thus the generated AST may not be up-to-date.