`make mostlyclean', to remove everything directly Halibut-generated

but not the CHM. It'll come in useful during the release process.

[originally from svn r7027]

CHECKLST.txt

@@ -140,9 +140,8 @@ of the tag.
     + change into the doc subdir
     + run `make VERSION="PuTTY release 0.XX" chm', then run `hhc
       putty.hhp' to build the .CHM
-    + then move the .CHM somewhere else so `make clean' doesn't blow
-      it away
-    + then run `make clean'
+    + then run `make mostlyclean' (destroys the hhc input files but
+      _not_ the .CHM)
     + then `make VERSION="PuTTY release 0.XX"'
 
  - Build the binary archives putty.zip (one for each architecture):

doc/Makefile

@@ -65,5 +65,7 @@ psftp.1: man-psft.but mancfg.but; $(MKMAN)
 puttytel.1: man-ptel.but mancfg.but; $(MKMAN)
 pterm.1: man-pter.but mancfg.but; $(MKMAN)
 
-clean:
-	rm -f *.html *.txt *.hlp *.cnt *.1 *.info vstr.but *.hh[pck] *.chm
+mostlyclean:
+	rm -f *.html *.txt *.hlp *.cnt *.1 *.info vstr.but *.hh[pck]
+clean: mostlyclean
+	rm -f *.chm