Annotation For Makefile

Origin for each line in Makefile from check-in acfc5037c6:

acfc5037c6 2019-05-02        rkeene: CPPFLAGS := -I. -DUSE_TCL_STUBS=1 -DXVFS_MODE=standalone
e5b6962adf 2019-05-02        rkeene: CFLAGS   := -fPIC -g3 -ggdb3 -Wall
e5b6962adf 2019-05-02        rkeene: LDFLAGS  :=
e5b6962adf 2019-05-02        rkeene: LIBS     := -ltclstub8.6
e5b6962adf 2019-05-02        rkeene: 
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
e5b6962adf 2019-05-02        rkeene: 	$(CC) $(CPPFLAGS) $(CFLAGS) -o example.o -c example.c
69e476dcd5 2019-05-02        rkeene: 
69e476dcd5 2019-05-02        rkeene: xvfs-core.o: xvfs-core.c xvfs-core.h Makefile
e5b6962adf 2019-05-02        rkeene: 	$(CC) $(CPPFLAGS) $(CFLAGS) -o xvfs-core.o -c xvfs-core.c
e90770a5a7 2019-05-02        rkeene: 
69e476dcd5 2019-05-02        rkeene: example.so: example.o xvfs-core.o Makefile
e5b6962adf 2019-05-02        rkeene: 	$(CC) $(CFLAGS) $(LDFLAGS) -shared -o example.so example.o xvfs-core.o $(LIBS)
e90770a5a7 2019-05-02        rkeene: 
f74a2e47ab 2019-05-02        rkeene: test: example.so
d121970301 2019-05-02        rkeene: 	echo 'if {[catch { load ./example.so Xvfs_example; source //xvfs:/example/main.tcl }]} { puts stderr $$::errorInfo; exit 1 }; exit 0' | tclsh
0a9369ff13 2019-05-02        rkeene: 
0a9369ff13 2019-05-02        rkeene: clean:
0a9369ff13 2019-05-02        rkeene: 	rm -f example.so example.o example.c
d121970301 2019-05-02        rkeene: 	rm -f xvfs-core.o
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