Just thought I'd mail this to save anyone else compiling their own 
kernel some time.

  It appears that you need the latest version of make 
(/usr/src/usr.bin/make) from netbsd-current to compile the latest source 
tree, otherwise it dies with "Unknown modifier 'Q'" errors when compiling 
the kern library.

(At least compiling the latest make made the errors go away!)

  If you all already know this, then many apologies :)

Ale.