Revert "CMDQ: Set the last entry in the linked list's next ptr to NULL."

This reverts commit f8ee85f.

This commit isn't needed, as calloc() zeros the memory for you.

src/libswd_cmdq.c

@@ -113,7 +113,6 @@ int libswd_cmdq_append(libswd_cmd_t *cmdq, libswd_cmd_t *cmd){
   cmdq->next=cmd;
   cmd->prev=cmdq;
  }
- cmd->next = NULL;
  return 1;
 }
 

src/libswd_core.c

@@ -61,7 +61,6 @@ libswd_ctx_t *libswd_init(void){
   libswd_deinit_ctx(libswdctx);
   return NULL;
  }
- libswdctx->cmdq->next = NULL;
  libswdctx->config.initialized=LIBSWD_TRUE;
  libswdctx->config.trnlen=LIBSWD_TURNROUND_DEFAULT_VAL;
  libswdctx->config.maxcmdqlen=LIBSWD_CMDQLEN_DEFAULT;