Really fix headers for __FreeBSD__
Really fix headers for __FreeBSD__

The symbol to detect FreeBSD is __FreeBSD__, not __FreeBSD.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git