tools/include: include stdint.h for SIZE_MAX in overflow.h

tools/include: include stdint.h for SIZE_MAX in overflow.h

tools/include/linux/overflow.h uses SIZE_MAX in its size helper functions.

Include stdint.h so tools users that include overflow.h without another
SIZE_MAX provider can build.

Link: https://lore.kernel.org/20260629022124.131894-3-chenyichong@uniontech.com
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>