Build with BSD make.
Don't hardcode CC or YACC.
A proper install routine.

Index: makefile
--- makefile.orig
+++ makefile
@@ -4,29 +4,18 @@
 # terms in the LICENSE file that is included in this source directory.
 # Tool documentation is available at http://spinroot.com
 
-CC=gcc
-CFLAGS?=-O2 -DNXT	# on some systems add: -I/usr/include
-			# on a PC:    make CFLAGS=-O2 -DNXT -DPC
-			# on Solaris: make CFLAGS=-O2 -DNXT -DSOLARIS
-			# on a Mac:   make CFLAGS=-O2 -DNXT -DMAC
-			# on HP-UX:   make CFLAGS=-O2 -DNXT -Aa
+CC?=gcc
+CFLAGS?=-O2 -DNXT
 
-			# debugging: make CFLAGS=-pg -g -DNXT
-
 # for a more picky compilation use gcc-4 and add:
 PICKY=-std=c99 -Wstrict-prototypes -pedantic -fno-strength-reduce \
 	-fno-builtin -W -Wshadow -Wpointer-arith \
 	-Wcast-qual -Winline -Wall
 
-# when running spin with a different compiler:
-			# on OS2:         spin -Picc -E/Pd+ -E/Q+
-			# for Visual C++: spin -PCL  -E/E
+YACC?=yacc
+YFLAGS=-v -d
+INSTALL?=install -c
 
-YACC=yacc		# on Solaris: /usr/ccs/bin/yacc
-YFLAGS=-v -d 		# creates y.output and y.tab.h
-DESTDIR?=/usr/local/bin
-INSTALL?=cp
-
 SPIN_OS= spinlex.o sym.o vars.o main.o msc_tcl.o \
 	mesg.o flow.o sched.o run.o pangen1.o pangen2.o \
 	pangen3.o pangen4.o pangen5.o guided.o dstep.o \
@@ -39,13 +28,16 @@ spin:	$(SPIN_OS) $(TL_OS) spin.o
 	$(CC) $(CFLAGS) -o spin spin.o $(SPIN_OS) $(TL_OS)
 
 install: spin
-	$(INSTALL) spin $(DESTDIR)
+	install -d -m 755 $(PREFIX)/bin
+	$(INSTALL) -s -m 755 spin $(PREFIX)/bin
+	install -d -m 755 $(PREFIX)/man/man1
+	$(INSTALL) -m 644 ../Man/spin.1 $(PREFIX)/man/man1
 
 spin.o:	spin.y
 	$(YACC) $(YFLAGS) spin.y
-	$(CC) $(CFLAGS) -c y?tab.c
-	rm -f y?tab.c
-	mv y?tab.o spin.o
+	$(CC) $(CFLAGS) -c y.tab.c
+	rm -f y.tab.c
+	mv y.tab.o spin.o
 
 $(SPIN_OS): spin.h spin.o
 
@@ -56,5 +48,5 @@ pangen1.o: pangen1.h pangen3.h pangen6.h
 pangen2.o: pangen2.h pangen4.h pangen5.h pangen7.h
 
 clean:
-	rm -f spin *.o y?tab.[ch] y.output y.debug
+	rm -f spin *.o y.tab.[ch] y.output y.debug
 	rm -f pan.[chmotb] a.out core *stackdump