Complex log builtins

[Paul Brook]

I just tried to make gfortran use the _Complex log builtins (clog, etc.), and 
discovered they don't exist.

The original post adding the other C99 math functions
(http://gcc.gnu.org/ml/gcc-patches/2003-09/msg00180.html)
Mentions conflicts with C++ iostreams clog.

However since these are C99 builtins they don't get enabled for C++ (right?). 
I enabled the builtins and tried various combinations of clog, 
std::clog, ::clog and using namespace std; and couldn't trigger any bad 
behaviour. The C99 clog was uniformly ignored.

Can these builtins (clog, clogf and clogl) be enabled?

Paul

P.S. If we do enable clog, we probably want to add clog10 as well.