iommufd/iommufd_private.h: Avoid -Wflex-array-member-not-at-end warning

JIRA: https://issues.redhat.com/browse/RHEL-131315

Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit b07bf25
Author: Gustavo A. R. Silva <gustavoars@kernel.org>
Date:   Mon Nov 10 20:35:31 2025 +0900

    iommufd/iommufd_private.h: Avoid -Wflex-array-member-not-at-end warning

    -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
    getting ready to enable it, globally.

    Move the conflicting declaration to the end of the corresponding
    structure. Notice that struct iommufd_vevent is a flexible
    structure, this is a structure that contains a flexible-array
    member.

    Fix the following warning:

    drivers/iommu/iommufd/iommufd_private.h:621:31: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

    Link: https://patch.msgid.link/r/aRHOAwpATIE0oajj@kspp
    Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
    Fixes: e36ba5a ("iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC")
    Reviewed-by: Kevin Tian <kevin.tian@intel.com>
    Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
    Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Signed-off-by: Eder Zulian <ezulian@redhat.com>

Author: efzrh

drivers/iommu/iommufd/iommufd_private.h

@@ -614,14 +614,16 @@ struct iommufd_veventq {
 	struct iommufd_eventq common;
 	struct iommufd_viommu *viommu;
 	struct list_head node; /* for iommufd_viommu::veventqs */
-	struct iommufd_vevent lost_events_header;
 
 	enum iommu_veventq_type type;
 	unsigned int depth;
 
 	/* Use common.lock for protection */
 	u32 num_events;
 	u32 sequence;
+
+	/* Must be last as it ends in a flexible-array member. */
+	struct iommufd_vevent lost_events_header;
 };
 
 static inline struct iommufd_veventq *