replace hard-coded nroff with $(NROFF)

sys/unix/Makefile.doc

@@ -48,15 +48,16 @@ GUIDE_PREFORMAT ?= cat $(GUIDEBOOK_MN) | $(NHGREP) | tbl tmac.n -
 # for Guidebook.dat, unpaginated version of Guidebook.txt
 ONEPAGE_PREFORMAT ?= cat Gbk-1pg-pfx.mn $(GUIDEBOOK_MN) Gbk-1pg-sfx.mn \
 	| $(NHGREP) | tbl tmac.n -
-ONEPAGECMD ?= $(ONEPAGE_PREFORMAT) | nroff -c -Tascii $(NROFF_FLAGS) | $(COLCMD)
+ONEPAGECMD ?= $(ONEPAGE_PREFORMAT) | $(NROFF) -c -Tascii $(NROFF_FLAGS) | $(COLCMD)
 # Use the "cat" GUIDECMD if nroff and/or tbl and/or col are not installed
 # Not appropriate for creating Guidebook.txt.
 # GUIDECMD ?= cat Guidebook.txt
 #
 # Single page. Might need adjustment to .pl value
-# GUIDECMD ?= $(GUIDE_PREFORMAT) | perl -pe 's/^(.mt)$$/.pl 4720v\n.in 0\n.po 8\n.ll 64m\n$$1/' | nroff -c -Tascii | $(COLCMD)
+# PLVALUE='s/^(.mt)$$/.pl 4720v\n.in 0\n.po 8\n.ll 64m\n$$1/'
+# GUIDECMD ?= $(GUIDE_PREFORMAT) | perl -pe $(PLVALUE) | $(NROFF) -c -Tascii | $(COLCMD)
 #
-GUIDECMD ?= $(GUIDE_PREFORMAT) | nroff -c -Tascii $(NROFF_FLAGS) | $(COLCMD)
+GUIDECMD ?= $(GUIDE_PREFORMAT) | $(NROFF) -c -Tascii $(NROFF_FLAGS) | $(COLCMD)
 GUIDEBOOK_TEX_SRC ?= Guidebook.tex
 GUIDEBOOK_TEX ?= $(GUIDEBOOK_TEX_SRC)
 
@@ -102,10 +103,10 @@ RCVRMANCREATE = cat recover.6 | $(NHGREP) >
 DLBMANCREATE = cat dlb.6 | $(NHGREP) >
 MDMANCREATE = cat makedefs.6 | $(NHGREP) >
 # manual installation for most SYSV-style systems
-# GAMEMANCREATE = cat nethack.6 | $(NHGREP) | nroff -man - >
-# RCVRMANCREATE = cat recover.6 | $(NHGREP) | nroff -man - >
-# DLBMANCREATE = cat dlb.6 | $(NHGREP) | nroff -man - >
-# MDMANCREATE = cat makedefs.6 | $(NHGREP) | nroff -man - >
+# GAMEMANCREATE = cat nethack.6 | $(NHGREP) | $(NROFF) -man - >
+# RCVRMANCREATE = cat recover.6 | $(NHGREP) | $(NROFF) -man - >
+# DLBMANCREATE = cat dlb.6 | $(NHGREP) | $(NROFF) -man - >
+# MDMANCREATE = cat makedefs.6 | $(NHGREP) | $(NROFF) -man - >
 
 manpages: $(PREMANPAGES)
 	-$(GAMEMANCREATE) $(MANDIR)/$(GAME).$(MANEXT)