logic : Fixed no indexed information saved for compilation database referencing certain compiler (issue #531)

* changed order of compiler flags for CDB indexer commands so that manually added flags are appended to the flags form the compile command.
* removed usage of clang::tooling::FixedCompilationDatabase and used CompilationDatabaseSingle for empty and cdb indexer commands.
* removed reference to a specific clang tool (e.g. "cl" or "cl.exe") from compile command and prepended "clang-tool" before running the indexer.

src/lib_cxx/project/SourceGroupCxxEmpty.cpp

@@ -63,6 +63,7 @@ std::vector<std::shared_ptr<IndexerCommand>> SourceGroupCxxEmpty::getIndexerComm
 				sourcePath,
 				indexedPaths,
 				excludedPaths,
+				m_settings->getProjectDirectoryPath(),
 				m_settings->getStandard(),
 				systemHeaderSearchPaths,
 				frameworkSearchPaths,