make -j fix for gcc/Makefile.in

[Jeffrey A Law]

  In message <200003300258.VAA04891@polya.math.purdue.edu>you write:
  > Now that alias.c includes tree.h, alias.o should depend on $(TREE_H).
  > 
  > 	* Makefile.in: Have alias.o depend on $(TREE_H).
Thanks.  Installed.
jeff