[clang-doc] Switch to default to all-TUs executor

Since we generally want to document a whole project, not just one file.

Differential Revision: https://reviews.llvm.org/D53170

llvm-svn: 345418
diff --git a/clang-tools-extra/clang-doc/tool/ClangDocMain.cpp b/clang-tools-extra/clang-doc/tool/ClangDocMain.cpp
index d8559aa..71ca2d9 100644
--- a/clang-tools-extra/clang-doc/tool/ClangDocMain.cpp
+++ b/clang-tools-extra/clang-doc/tool/ClangDocMain.cpp
@@ -31,7 +31,6 @@
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "clang/Tooling/Execution.h"
-#include "clang/Tooling/StandaloneExecution.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/Support/CommandLine.h"
@@ -169,6 +168,7 @@
   llvm::sys::PrintStackTraceOnErrorSignal(argv[0]);
   std::error_code OK;
 
+  ExecutorName.setInitialValue("all-TUs");
   auto Exec = clang::tooling::createExecutorFromCommandLineArgs(
       argc, argv, ClangDocCategory);