linux: reduce the number of includes

Forward declare the three data structs and thus avoid to include
nvme/ioctl.h and nvme/types.h. This reduces the inter dependencies
between the headers and simplifies any porting attempts.

Signed-off-by: Daniel Wagner <[email protected]>

Author: igaw

libnvme/src/nvme/linux.h

@@ -6,14 +6,14 @@
  * Authors: Keith Busch <[email protected]>
  *	    Chaitanya Kulkarni <[email protected]>
  */
-#ifndef _LIBNVME_LINUX_H
-#define _LIBNVME_LINUX_H
+#pragma once
 
 #include <stddef.h>
-#include <stdio.h>
+#include <stdbool.h>
 
-#include <nvme/ioctl.h>
-#include <nvme/types.h>
+struct nvme_transport_handle;
+struct nvme_passthru_cmd;
+struct nvme_global_ctx;
 
 /**
  * DOC: linux.h
@@ -555,5 +555,3 @@ void nvme_set_dry_run(struct nvme_global_ctx *ctx, bool enable);
  * IOCTL probing is enabled per default.
  */
 void nvme_set_ioctl_probing(struct nvme_global_ctx *ctx, bool enable);
-
-#endif /* _LIBNVME_LINUX_H */