Fix homebrew include path.

[stefanseefeld]

No description provided.

[pdimov]

This seems to have worked, but the build now fails for a different reason, Optional requires C++11. I see that the command line passes cxxflags=-std=c++11, but then the log says

configuration check results:
  has_cxx11 : False 
  has_numpy : False 

so it looks like this doesn't take for some reason.

Maybe faber should be modified to print the command line on failure, like b2 does.

The problem could be that the makedep rule doesn't apply cxxflags.

[stefanseefeld]

Good catch @pdimov . Indeed, faber uses the cppflags feature to configure the pre-processor, and cxxflags for the (C++) compiler. Setting the -std option in both has fixed the build problem. Thanks !