- Add libstdcpp feature to indicate a platform is providing a libstdc++
implementation ready for use
- The existing cpp feature now only indicates a working C++ toolchain without
libstdc++. (E.g. still useful for the Arduino compatibility layer.)
- Added libstdcpp as required feature were needed
- Added some documentation on C++ on RIOT
Rename the variable to make it clearer that it refers to the last Makefile
included.
Usually this is the current file, but when another Makefile is included this
changes.
