compiler:c++11-lib option

[Fernando Apesteguía]

Hi,

I'm having some troubles making graphics/code-eli to compile on
anything below 10.0-RELEASE. The port uses some c++11 functions
(std::cbrt) so I put this line in the Makefile:

USES=           compiler:c++11-lib

However, when I try to compile the port in 9.3, it complains about
cstdlib not being found.

Am I using the option in correctly? What is the expected behavior for
a port that specifies that option in anything below 10?

Thanks in advance.