data: Option to run only C/C++ preprocessor when indexing (issue 297)

* Added as checkbox to indexing start dialog
* Only shown for C/C++ projects
* Files will be marked incomplete

src/lib/data/indexer/Indexer.h

@@ -57,7 +57,7 @@ std::shared_ptr<IntermediateStorage> Indexer<IndexerCommandType, ParserType>::in
 
 	parserClient->resetStorage();
 
-	if (parserClient->hasFatalErrors())
+	if (parserClient->hasFatalErrors() || indexerCommand->preprocessorOnly())
 	{
 		storage->setAllFilesIncomplete();
 	}

src/lib/data/indexer/IndexerCommand.h

@@ -21,6 +21,9 @@ public:
 	bool cancelOnFatalErrors() const;
 	void setCancelOnFatalErrors(bool cancelOnFatalErrors);
 
+	virtual bool preprocessorOnly() const = 0;
+	virtual void setPreprocessorOnly(bool preprocessorOnly) = 0;
+
 private:
 	FilePath m_sourceFilePath;
 	std::set<FilePath> m_indexedPaths;