The pointers Atomspace, Spospspace, Snegspace, Arrayspace can be removed (#402)

These pointers are neither initialized nor referenced anywhere in the code.

src/main.c

@@ -75,7 +75,6 @@
 DLword *Lisp_world; /* lispworld */
 
 /********** 68k address for Lisp Space **********/
-DLword *Atomspace;
 DLword *Stackspace;
 DLword *Plistspace;
 DLword *DTDspace;
@@ -85,8 +84,6 @@ DLword *Pnamespace;
 DLword *AtomSpace;
 DLword *Defspace;
 DLword *Valspace;
-DLword *Spospspace;
-DLword *Snegspace;
 
 /********** For Virtual Memory Management **********/
 #ifdef BIGVM
@@ -124,7 +121,6 @@ DLword *HTcoll;
 DLword *DisplayRegion;
 int DisplayInitialized = NIL;
 
-DLword *Arrayspace;
 DLword *MDS_space_bottom;
 DLword *PnCharspace;
 struct dtd *ListpDTD;

src/mkatom.c

@@ -267,7 +267,6 @@ LispPTR compare_lisp_chars(register const char *char1, register const char *char
 LispPTR make_atom(const char *char_base, DLword offset, DLword length, short int non_numericp)
 /* if it is NIL then these chars are treated as NUMBER */
 {
-  extern DLword *Spospspace;
   extern DLword *AtomHT;
   extern DLword *Pnamespace;
   extern DLword *AtomSpace;