Permit a discontiguous stack which is grown automatically as needed.

The stack will have a guaranteed zone which is always available. The size of the guard area will be target specific. It will include enough stack space to actually allocate more stack space. Each function will have to verify that
it has enough space in the current stack to execute.

Makefile

@@ -2,7 +2,7 @@
 CFLAGS = -fPIC -Iinclude -I. -W -Wunused -Wall
 
 # Additional CFLAGS for debug build
-DCFLAGS = -O0 -g3
+DCFLAGS = -O0 -g3 -fsplit-stack
 
 # Addditional CFLAGS for release build
 RCFLAGS = -O3 -s