MFC r331651-r331653

r331651:
Copy flags over ifr_union directly rather than via casts through
ifr_data.

No functional change in practice. If the sbni driver supported
64-bit big-endian system, this would be an ABI changes, but it is
i386-only. The old version leaked a word of stack on 64-bit systems.

This eliminates the only assignment to ifr_data.

r331652:
Revert r331651 to recommit with proper commit metadata.

r331653:
Copy flags over ifr_union directly rather than via casts through
ifr_data.

No functional change in practice. If the sbni driver supported
64-bit big-endian system, this would be an ABI changes, but it is
i386-only. The old version leaked a word of stack on 64-bit systems.

This eliminates the only assignment to ifr_data.

Reviewed by: kib
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14874