dos/sys: got rid of the "next" symbol

src/p_sys.cpp

@@ -77,7 +77,6 @@ void PackSys::patchLoader(OutputFile *fo,
         throwNotCompressible();
 
     // use some fields of the original file
-    linker->defineSymbol("next", get_le32(ibuf));
     linker->defineSymbol("attribute", get_le16(ibuf + 4));
     linker->defineSymbol("interrupt", get_le16(ibuf + 8));
 

src/stub/src/i086-dos16.sys.asm

@@ -43,7 +43,7 @@
 
 section         SYSMAIN1
 start:
-                .long   next
+                .long   -1
                 .short  attribute
                 .short  strategy        /* .sys header */
                 .short  interrupt       /* opendos wants this field untouched */