Having re-bootstrapped the system, a new problem has occurred: I can't build any package that includes C++ code.
I've now fixed this by altering /mk/compiler.mk, changing: ALL_ENV+= CXXCPP="${CPP:Q} -E" to ALL_ENV+= CXXCPP="CC -E" ... but this still suggests that my setting for $CPP is wrong, I guess? Cheers, stuart