Create storage.h to declare functions defined in storage.c

Update files that depend on storage functions to include storage.h
Declare as static all functions in storage.c that are not needed externally.
Add dependencies to makefile-tail.

	modified:   makefile-tail
	new file:   ../inc/storage.h
	modified:   ../src/allocmds.c
	modified:   ../src/gchtfind.c
	modified:   ../src/llstk.c
	modified:   ../src/main.c
	modified:   ../src/storage.c
	modified:   ../src/subr.c

inc/storage.h

@@ -0,0 +1,4 @@
+void checkfor_storagefull(register unsigned int npages);
+LispPTR dremove(LispPTR x, LispPTR l);
+LispPTR newpage(LispPTR base);
+void init_storage(void);