cann't compile c++11 code

- VS Code Version:1.46.0
- OS Version:Mac OS 10.15.4
- Code Runner Version:0.10.0

**Describe the bug**
Cann't compile the following c++11 code
`
#include
#include

int main () {
std::unordered_map mymap;
mymap = {{"Australia","Canberra"},{"U.S.","Washington"},{"France","Paris"}};
}
`
Description of what the bug is.
when compile c++11 code ,it should add -std=c++11 compile flag

**To Reproduce**
Steps to reproduce the behavior:

1. write c++11 code
2. compile it