[Bug libstdc++/59087] Issues including complex.h in C++11/1y mode because of C's complex.h

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59087

--- Comment #10 from Marc Glisse <glisse at gcc dot gnu.org> ---
It seems to me that this is ok now.

* If you want <complex>, include that, not <complex.h>
* <complex.h> contains the C stuff for compatibility with C code, C code
doesn't include <ccomplex>, so <ccomplex> doesn't need that stuff (it wouldn't
make sense to move those non-standard functions to namespace std)
* The error message now advertises the option that lets complex suffixes
compile
* The files using unsafe identifiers (conflicts with macros) now use uglified
names instead

I am not planning to do a backport myself of those 2 trivial patches, but if
anyone wants to, feel free to do it.

We may have to revisit some decisions when the standard (C++14? C++17?) will
provide UDLs that conflict with the complex suffixes.