Add 2020/endoh3/run_clock.alt.sh for alt code

The alt code provided by the author back in 2020 uses Unicode but there
wasn't a script for it (the script run_clock.sh which I made some fixes
in last year was added by the judges but no version for the alt code was
added).

The scripts also have another fix in them: make clock or make clock.alt
first as if not and the program does not exist the script will happily
overwrite the C files and prevent it from being compiled. They use 'make
-B' just to be sure that it's compiled.

2020/endoh3/Makefile

@@ -113,8 +113,8 @@ OBJ= ${PROG}.o
 DATA=
 TARGET= ${PROG} clock
 #
-ALT_OBJ= ${PROG}.alt.o
-ALT_TARGET= ${PROG}.alt
+ALT_OBJ= ${PROG}.alt.o clock.alt.o
+ALT_TARGET= ${PROG}.alt clock.alt
 
 
 #################
@@ -146,6 +146,14 @@ alt: data ${ALT_TARGET}
 ${PROG}.alt: ${PROG}.alt.c
 	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
 
+clock.alt: clock.alt.c
+
+clock.alt.c: ${PROG}.alt.c
+	@${RM} -f $@
+	${CP} -f $< $@
+
+
+
 # data files
 #
 data: ${DATA}