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/data/indexer/interprocess/shared_types/SharedIndexerCommand.cpp

@@ -27,6 +27,7 @@ void SharedIndexerCommand::fromLocal(IndexerCommand* indexerCommand)
 		IndexerCommandCxxEmpty* cmd = dynamic_cast<IndexerCommandCxxEmpty*>(indexerCommand);
 
 		setType(CXX_EMPTY);
+		setWorkingDirectory(cmd->getWorkingDirectory());
 		setLanguageStandard(cmd->getLanguageStandard());
 		setCompilerFlags(cmd->getCompilerFlags());
 		setSystemHeaderSearchPaths(cmd->getSystemHeaderSearchPaths());
@@ -69,6 +70,7 @@ std::shared_ptr<IndexerCommand> SharedIndexerCommand::fromShared(const SharedInd
 			indexerCommand.getSourceFilePath(),
 			indexerCommand.getIndexedPaths(),
 			indexerCommand.getExcludedPaths(),
+			indexerCommand.getWorkingDirectory(),
 			indexerCommand.getLanguageStandard(),
 			indexerCommand.getSystemHeaderSearchPaths(),
 			indexerCommand.getFrameworkSearchhPaths(),