Re-use the remaining WorkSpace for each term through Generator

Generator consumes WorkSpace, so here we run out very easily if we
don't reset the position that we use, each iteration.

sources/optimize.cc

@@ -4453,15 +4453,19 @@ WORD generate_expression (WORD exprnr) {
 	// scan for the original expression (marked by *t<0) and give the
 	// terms to Generator
 	WORD *t = AO.OptimizeResult.code;
-    {
+	{
 		WORD old = AR.Cnumlhs; AR.Cnumlhs = 0;
+		// We can use the remaining part of the WorkSpace for every term that
+		// goes through Generator. We have WorkSpace problems here if we use
+		// the (modified) AT.WorkPointer every time in the loop.
+		WORD* currentWorkPointer = AT.WorkPointer;
 		while (*t!=0) {
 			bool is_expr = *t < 0;
 			t++;
 			while (*t!=0) {
 				if (is_expr) {
-					memcpy(AT.WorkPointer, t, *t*sizeof(WORD));
-					Generator(BHEAD AT.WorkPointer, C->numlhs);
+					memcpy(currentWorkPointer, t, *t*sizeof(WORD));
+					Generator(BHEAD currentWorkPointer, C->numlhs);
 				}
 				t+=*t;
 			}