Add 2020 source files for real

2020/endoh3/run_clock.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+while true; do
+cc -std=c11 -Wall -Wextra -pedantic -O3 clock.c -o clock
+clear
+./clock | tee clock.c
+sleep 5
+done