proposed bootstrap changes

[DJ Delorie]

Something like this?

unstage2:
	-if test -d stage2; then \
	  for i in stage2/* ; do \
	    if test -d stage2/$i; then \
	      mv stage2/$i/* $i/.; \
	    else \
	      mv stage2/$i .; \
	    fi \
	  done \
	fi
	-rm -rf stage2 stage3 stage4 stage2_build stage2_copy

restage2: unstage2
	$(MAKE) LANGUAGES="$(LANGUAGES)" stage2_build

Any more complex and we'd need a script for recursion.

I'd rather just do "restage2: unstage2 stage2_build" but that breaks
with -j.  Any suggestions?