Annotation For Makefile

Origin for each line in Makefile from check-in 69e476dcd5:

0a9369ff13 2019-05-02        rkeene: all: example.so
0a9369ff13 2019-05-02        rkeene: 
e90770a5a7 2019-05-02        rkeene: example.c: $(shell find example -type f) $(shell find lib -type f) xvfs.c.rvt xvfs-create Makefile
0a9369ff13 2019-05-02        rkeene: 	./xvfs-create --directory example --name example > example.c.new
0a9369ff13 2019-05-02        rkeene: 	mv example.c.new example.c
0a9369ff13 2019-05-02        rkeene: 
e90770a5a7 2019-05-02        rkeene: example.o: example.c xvfs-core.h Makefile
f74a2e47ab 2019-05-02        rkeene: 	cc -fPIC -Wall -I. -o example.o -c example.c
f74a2e47ab 2019-05-02        rkeene: 
69e476dcd5 2019-05-02        rkeene: xvfs-core.o: xvfs-core.c xvfs-core.h Makefile
69e476dcd5 2019-05-02        rkeene: 	cc -fPIC -Wall -I. -o xvfs-core.o -c xvfs-core.c
69e476dcd5 2019-05-02        rkeene: 
69e476dcd5 2019-05-02        rkeene: example.so: example.o xvfs-core.o Makefile
69e476dcd5 2019-05-02        rkeene: 	cc -fPIC -shared -o example.so example.o xvfs-core.o
e90770a5a7 2019-05-02        rkeene: 
f74a2e47ab 2019-05-02        rkeene: test: example.so
f74a2e47ab 2019-05-02        rkeene: 	echo 'load ./example.so Xvfs_example; puts OK' | tclsh | grep '^OK$$'
0a9369ff13 2019-05-02        rkeene: 
0a9369ff13 2019-05-02        rkeene: clean:
0a9369ff13 2019-05-02        rkeene: 	rm -f example.so example.o example.c
0a9369ff13 2019-05-02        rkeene: 
0a9369ff13 2019-05-02        rkeene: distclean: clean
0a9369ff13 2019-05-02        rkeene: 
0a9369ff13 2019-05-02        rkeene: .PHONY: all clean distclean test