Just for reference in the future, the help documentation gives you this information.
You can find it under Help -> Help Contents -> Developer Studio User Guide -> Build System -> Advanced Topics -> Adding C++ Code
The Header “Tool Chain Specifics” deals with the extra code you need depending on the Target Mode.
If you are using ARM EABI GCC then it should link you to the file “/com.wavecom.openat.ide.ebs.ui.help/html/eabi_stub.c”