tests: preallocate vector size

tests/cppaql/arbologyTest.cpp

@@ -113,6 +113,7 @@ static std::string search_replace ( std::string text, const std::string & search
 static std::vector < std::pair < std::string, std::string > > pair_pattern_subject ( const std::vector < std::string > & files, const std::string & pattern, const std::string & subj ) {
 	std::vector < std::pair < std::string, std::string > > res;
+	res.reserve ( files.size ( ) );
 	for ( const auto & file : files )
 		res.emplace_back ( file, search_replace ( file, pattern, subj ) );