remove commentary that is now in the wiki

Makefile

@@ -18,87 +18,6 @@ show:
 
 else
 
-# The problem we need to solve is as follows.  
-#
-# GNU make supports included Makefiles, and it is clever enough to try
-# to update those Makefiles when they are out-of-date or missing.  It
-# first reads all the Makefiles, and then tries to build each one if
-# it is out-of-date, using the rules in the Makefiles themselves.
-# When it has brought all the Makefiles up-to-date, it restarts itself
-# to read the newly-generated Makefiles.
-#
-# This works fine, unless there are dependencies *between* the
-# Makefiles.  For example in the GHC build, for each package we have a
-# package-data.mk file which is generated by the ghc-cabal program,
-# and we have a .depend file.  The .depend file cannot be generated
-# until package-data.mk has been generated and make has been restarted
-# to read in its contents, because it is the package-data.mk file that
-# tells us which modules are in the package.  But make always makes
-# all the Makefiles before restarting - it doesn't take into account a
-# dependency between Makefiles and restart itself earlier.
-
-# Consider the following makefile:
-
-# --------------------
-# all :
-#
-# include inc1.mk
-# 
-# inc1.mk : Makefile
-# 	echo "X = C" >$@
-# 
-# include inc2.mk
-# 
-# inc2.mk : inc1.mk
-# 	echo "Y = $(X)" >$@
-# --------------------
-
-# Now try it:
-# 
-# $ make -f fail.mk
-# fail.mk:3: inc1.mk: No such file or directory
-# fail.mk:8: inc2.mk: No such file or directory
-# echo "X = C" >inc1.mk
-# echo "Y = " >inc2.mk
-# make: Nothing to be done for `all'.
-
-# make built both inc1.mk and inc2.mk without restarting itself
-# between the two (even though we added a dependency on inc1.mk from
-# inc2.mk).
-#
-# The solution we adopt in the GHC build system is essentially this:
-
-# --------------------
-# PHASE = 0
-# 
-# ifeq "$(PHASE)" "0"
-# all :
-# 	$(MAKE) PHASE=1
-# else
-# all :
-# endif
-# 
-# -include inc1.mk
-# 
-# inc1.mk : Makefile
-# 	echo "X = C" >$@
-# 
-# ifneq "$(PHASE)" "0"
-# include inc2.mk
-# 
-# inc2.mk : inc1.mk
-# 	echo "Y = $(X)" >$@
-# endif
-# 
-# clean :
-# 	rm -f inc1.mk inc2.mk
-# --------------------
-
-# That is, every time make is invoked, we force it to update inc1.mk
-# and then restart.  In the GHC build system we need to divide the
-# build into 4 phases in fact, with a restart between each phase.  See
-# ghc.mk for the details on what happens in each phase and why.
-
 default : all
 	@: