Is there any reason bsd.pkg.mk doesn't define

	CFLAGS+=-I${PREFIX}/include automatically?

The result of not doing this is hard code the above code snippit in the
Makefiles of most packages with a compile-time dependency -- where it can
not be changed easily if ${PREFIX}/include is not appropriate -- for instance
if the user is installing somewhere other than /usr/pkg, but compiling from
dependencies already installed in /usr/pkg

Cheers,
Julian.