Fix memory leak in file analyzer.

This undoes the changes applied in merge 9db27a6d60
and goes back to the state in the branch as of the merge 5ab3b86.

Getting rid of the additional layer of removing analyzers and just
keeping them in the set introduced subtle differences in behavior since
a few calls were still passed along. Skipping all of these with SetSkip
introduced yet other subtle behavioral differences.

src/file_analysis/File.h

@@ -119,6 +119,11 @@ public:
 	 */
 	bool RemoveAnalyzer(file_analysis::Tag tag, RecordVal* args);
 
+	/**
+	 * Signal that this analyzer can be deleted once it's safe to do so.
+	 */
+	void DoneWithAnalyzer(Analyzer* analyzer);
+
 	/**
 	 * Pass in non-sequential data and deliver to attached analyzers.
 	 * @param data pointer to start of a chunk of file data.
@@ -287,6 +292,7 @@ protected:
 	bool postpone_timeout;     /**< Whether postponing timeout is requested. */
 	bool done;                 /**< If this object is about to be deleted. */
 	AnalyzerSet analyzers;     /**< A set of attached file analyzers. */
+	std::list<Analyzer *> done_analyzers; /**< Analyzers we're done with, remembered here until they can be safely deleted. */
 
 	struct BOF_Buffer {
 		BOF_Buffer() : full(false), size(0) {}