[PATCH] Use -std=c++11 when no arguments are provided.

[Guillaume Papin]

================
Comment at: cpp11-migrate/tool/Cpp11Migrate.cpp:237-238
@@ +236,4 @@
+    } else {
+      Compilations.reset(CompilationDatabase::autoDetectFromSource(
+          SourcePaths[0], ErrorMessage));
+      // If no compilation database can be detected from source then we create
----------------
I believe these lines should be before the else and you still have to check for the emptiness of BuildPath.

The `cpp11-migrate -help` says:

  -p <build-path> is used to read a compile command database.

        <...>. When no build path is specified, a search for compile_commands.json
        will be attempted through all parent paths of the first input file .


http://llvm-reviews.chandlerc.com/D1337