Bug Description

The toolchain fails to build c++ files correctly when using -isystem, as it treats all headers as being wrapped in `extern "C"`. Other versions of gcc (x86, linaro arm-linux, etc) handles this use case. It seems to be solved on upstreams versions of gcc, but not on this arm-none-eabi version.

I've tested it with 6-2016-q4-major, and 6-2017-q1-update.

related threads:

https:/ /gcc.gnu. org/ml/ gcc-patches/ 2012-06/ msg01159. html

https:/ /gcc.gnu. org/ml/ gcc-help/ 2016-02/ msg00002. html