Update to v4.19 kernel headers.

Test: Builds and boots.
Change-Id: I99a9ed79666e143b47f02ca4e59eed94f69b7e4a
(cherry picked from commit a981e2e52e2e95a65fa9c9b6fb16dcb4c83dd576)
diff --git a/libc/kernel/uapi/linux/virtio_config.h b/libc/kernel/uapi/linux/virtio_config.h
index 80a0b1b..ddf5e4e 100644
--- a/libc/kernel/uapi/linux/virtio_config.h
+++ b/libc/kernel/uapi/linux/virtio_config.h
@@ -26,11 +26,12 @@
 #define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
 #define VIRTIO_CONFIG_S_FAILED 0x80
 #define VIRTIO_TRANSPORT_F_START 28
-#define VIRTIO_TRANSPORT_F_END 34
+#define VIRTIO_TRANSPORT_F_END 38
 #ifndef VIRTIO_CONFIG_NO_LEGACY
 #define VIRTIO_F_NOTIFY_ON_EMPTY 24
 #define VIRTIO_F_ANY_LAYOUT 27
 #endif
 #define VIRTIO_F_VERSION_1 32
 #define VIRTIO_F_IOMMU_PLATFORM 33
+#define VIRTIO_F_SR_IOV 37
 #endif