Fix 2019/karns

A strange problem is that although it worked with macOS and linux for me
numerous times in the past it stopped working under both. I went to try
and figure it out but when disabling the optimiser for debug symbols the
problem vanished. Changing it back to -O3 and the problem reappeared
both with macOS and linux. Thus it appears that the entry should not
have -O level > 0. I'm not sure if this is the same issue the author
reported where it sometimes segfaults but I did not try and figure it
out either (in any event the crash disappeared when -O0 was specified so
it'd be harder to debug).

Added to .gitignore the file the author noted the program is called (as
the command he gives creates). To make it easier I just made it a
symlink to prog.

Fixed formatting in README.md.

2019/karns/Makefile

@@ -68,7 +68,7 @@ CINCLUDE=
 
 # Optimization
 #
-OPT= -O3
+OPT= 
 
 # Default flags for ANSI C compilation
 #
@@ -120,6 +120,10 @@ TARGET= ${PROG}
 ALT_OBJ=
 ALT_TARGET=
 
+############################
+# FORCE no -O level        #
+# ##########################
+COPT+= -O0
 
 #################
 # build the entry
@@ -134,6 +138,11 @@ all: data ${TARGET}
 
 ${PROG}: ${PROG}.c
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
+	${LN} -sf ${PROG} tbfs
+
+test: prog
+	${CAT} prog.c | ./prog
+
 
 # alternative executable
 #