virtualbox and non-default compiler

[Andriy Gapon]

There is another issue with building virtualbox-ose port using a non-default
compiler.  CFLAGS/CXXFLAGS and LDFLAGS defined by ports framework (and user) are
not passed to virtualbox build at all.
So, whatever bsd.gcc.mk carefully configures for e.g. gcc46 is not reflected in
the build.  Most importantly this is -Wl,-rpath option in LDFLAGS that should
ensure that the correct C++ run-time libraries are picked up.

I do not know how pass those make variables to kBuild-based virtualbox build.

-- 
Andriy Gapon