CC and CXX env variables are not respected when building GC about asymptote

[johncbowman]

Thanks; I added this patch (without CFLAGS and CXXFLAGS, to avoid compilation errors).

[mojca]

Commit: 0d7435b

Thank you very much. The only remaining "problem" is that a standard way to compile for a different architecture on Mac is usually something like

export CFLAGS="-arch i386"
export CXXFLAGS="-arch i386"
export LDFLAGS="-arch i386"

or (used by MacPorts)

export CPPFLAGS="-arch i386"

and those flags wouldn't be promoted to GC builds. But I have to give this a bit more thought. A valid way to achieve the goal is still

export CC="clang -arch i386"
export CXX="clang++ -arch i386"

For now that should do it. Thank you very much for accepting the patch.