V3 PATCH: #undef some C99 math macros in <cmath>

[Benjamin Kosnik]

> I understand.  But isn't that a linux-centric solution?

Well. Yes. 

As uli already indicated, your approach is valid. The rest of this stuff 
should get cleaned up too, but after your patch is in.

I like the idea of putting the C99 bits into a "c99" namespace and 
aliasing them into std:: if the user configures with --enable-c99. I 
think that sounds pretty reasonable. As I understand it, C99 
compatibility is something that the library group intends to look at.

-benjamin