Change __inline style to be consistent with FreeBSD usage,
and also fix gcc build (on STABLE, when MFCd).

PR:	192880
Reviewed by:	neel
Reported by:	ngie
MFC after:	1 day


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270438 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f