[NFC][modules] Create objects on the stack (llvm#124034)

`ClangTool` change to fix memory leak.
`FixedCompilationDatabase` changed just to makes it simpler.

Author: vitalybuka

clang-tools-extra/modularize/CoverageChecker.cpp

@@ -278,15 +278,15 @@ CoverageChecker::collectUmbrellaHeaderHeaders(StringRef UmbrellaHeaderName) {
     sys::fs::current_path(PathBuf);
 
   // Create the compilation database.
-  std::unique_ptr<CompilationDatabase> Compilations;
-  Compilations.reset(new FixedCompilationDatabase(Twine(PathBuf), CommandLine));
+  FixedCompilationDatabase Compilations(Twine(PathBuf), CommandLine);
 
   std::vector<std::string> HeaderPath;
   HeaderPath.push_back(std::string(UmbrellaHeaderName));
 
   // Create the tool and run the compilation.
-  ClangTool Tool(*Compilations, HeaderPath);
-  int HadErrors = Tool.run(new CoverageCheckerFrontendActionFactory(*this));
+  ClangTool Tool(Compilations, HeaderPath);
+  CoverageCheckerFrontendActionFactory ActionFactory(*this);
+  int HadErrors = Tool.run(&ActionFactory);
 
   // If we had errors, exit early.
   return !HadErrors;