Added a NULL check at one point in the SPICE read routine that

prevents a segfault under some condition (not fully investigated)
involving .include files.  Appears to resolve the problem without
any unintended consequences.

base/spice.c

@@ -532,6 +532,7 @@ void ReadSpiceFile(char *fname, int filenum, struct cellstack **CellStackPtr,
 
     SkipTok(NULL); /* get the next token */
     if ((EndParseFile()) && (nexttok == NULL)) break;
+    if (nexttok == NULL) break;
 
     if (nexttok[0] == '*') SkipNewLine(NULL);