Compiling gnu diction on Cygwin

[Keith Christian]

Brian, Csaba, I was able to complete the compile with your assistance.

Brian: I'll experiment with your suggestions of:  #include <stdlib.h>
and remove casts (should not normally be required or used in C) as
well.
Csaba:  Adding the -Wall -Wpedantic -Wextra fixed the issue, thanks.

This will help a great deal as I pursue troubleshooting failed C compiles.

THANKS!