[2.16.1-alpha] Cannot make debugging build

I did not find `realclean' option for the makefile, so did
  ./Configure
  make bench
  make clean
  ./Configure -g
  make

but it would not make debugging build.  AFAICS, the reason is that
  config/objdir
(sp???) remains the same, so the build happens with the non-debugging
Makefile. 

What did I do wrong?

Thanks,
Ilya