Improve 1988/westley/demo.sh

In addition to exiting (1) on compilation error (rather than trying to
run the program) don't use -Wall -Wextra and don't redirect stderr to
/dev/null. This way if there ever is a problem compiling it can be seen.

Another option might be to first check if the program is already
compiled but this might not be that important. This can be determined
later.

1988/westley/demo.sh

@@ -7,7 +7,7 @@ cat westley.c
 sleep 1
 
 echo "$ cc westley.c -o westley"
-cc -std=gnu89 -Wall -Wextra -pedantic -Wno-error -Wno-implicit-function-declaration -Wno-return-type    -O3 westley.c -o westley 2>/dev/null
+cc -std=gnu89 -Wno-error -Wno-implicit-function-declaration -Wno-return-type    -O3 westley.c -o westley || exit 1
 
 echo "$ ./westley"
 ./westley