Intitialize $(tmac_s_ and $(tmac_m). Use the initialized variable $(device)

instead of the uninitialized one $(DEVICE).

I hoped these changes would fix some of the large runtime macro processing
bugs, but they seem to only fix some small build-time macro substitution
bugs.  E.g., `man ms' now tells you to invoke groff with the flags `-ms'
instead of the bogus flags `-m'; `man groff now tells you that the default
device is `ps' instead of the bogus device `'.

gnu/usr.bin/groff/Makefile.cfg

@@ -41,6 +41,8 @@ DVIPRINT=lpr -d
 # Don't touch...
 
 g=
+tmac_s=s
+tmac_m=m
 device=ps
 fontdir=/usr/share/groff_font
 fontpath=$(fontdir)
@@ -106,7 +108,7 @@ CFLAGS+=$(DEFINES)
 	-e "s;@FONTPATH@;$(fontpath);g" \
 	-e "s;@MACRODIR@;$(tmacdir);g" \
 	-e "s;@MACROPATH@;$(tmacpath);g" \
-	-e "s;@DEVICE@;$(DEVICE);g" \
+	-e "s;@DEVICE@;$(device);g" \
 	-e "s;@DEFAULT_INDEX@;$(indexdir)/$(indexname);g" \
 	-e "s;@DEFAULT_INDEX_NAME@;$(indexname);g" \
 	-e "s;@INDEX_SUFFIX@;$(indexext);g" \