support for RPi: fix C++ support

templates/concurrency_view/rpi_cgpr/partition.tmplt

@@ -68,7 +68,7 @@ configuration project Raspberry_PI is
       for Driver ("C++") use "arm-linux-gnueabihf-g++";
 
       for Leading_Required_Switches ("C") use ("-c", "-x", "c");
-      for Leading_Required_Switches ("C++") use ("-c", "-x", "c");
+      for Leading_Required_Switches ("C++") use ("-c", "-x", "c++");
       for Required_Switches("Ada") use ("-c", "-x", "ada");
 
       Common_C_Switches :=