Get rid of HDR variable

The HDR variable is used for general purpose headers, which are not
given in this project. arg.h and config.h are only needed for
slstatus.c, not every component $(COM:=.c).

This also fixes a problem introduced in
e04a3853643df1c98a451969d515d8850f138bcc, where config.h is pulled into
the tarball.

Makefile

@@ -5,7 +5,6 @@
 include config.mk
 
 REQ = util
-HDR = arg.h config.h
 COM =\
 	battery\
 	cpu\
@@ -30,8 +29,8 @@ COM =\
 all: slstatus
 
 slstatus: slstatus.o $(COM:=.o) $(REQ:=.o)
-slstatus.o: slstatus.c slstatus.h $(HDR) $(REQ:=.h)
-$(COM:=.o): config.mk $(HDR) $(REQ:=.h)
+slstatus.o: slstatus.c slstatus.h arg.h config.h $(REQ:=.h)
+$(COM:=.o): config.mk $(REQ:=.h)
 
 config.h:
 	cp config.def.h $@
@@ -49,7 +48,7 @@ dist:
 	rm -rf "slstatus-$(VERSION)"
 	mkdir -p "slstatus-$(VERSION)"
 	cp -R LICENSE Makefile README config.mk config.def.h \
-	      $(HDR) slstatus.c $(COM:=.c) $(REQ:=.c) $(REQ:=.h) \
+	      arg.h slstatus.c $(COM:=.c) $(REQ:=.c) $(REQ:=.h) \
 	      slstatus.1 "slstatus-$(VERSION)"
 	tar -cf - "slstatus-$(VERSION)" | gzip -c > "slstatus-$(VERSION).tar.gz"
 	rm -rf "slstatus-$(VERSION)"