Allow Tru64 UNIX bootstrap with C++

[Ian Lance Taylor]

Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> writes:

> 2011-07-21  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
>
> 	gcc:
> 	* system.h [__cplusplus]: Wrap C function declarations in extern "C".
>
> 	include:
> 	* xregex.h (regoff_t): Define.

This is OK.

I'll preapprove a similar patch to libcpp/system.h if you want to take a
look at that.

Thanks.

Ian