Changes to make openzfs build within FreeBSD buildworld

A collection of header changes to enable FreeBSD to build
with vendored OpenZFS.

Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #10635

include/os/freebsd/spl/sys/simd_x86.h

@@ -29,7 +29,11 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>
 #include <sys/systm.h>
+#ifdef __i386__
+#include <x86/fpu.h>
+#else
 #include <machine/fpu.h>
+#endif
 #include <x86/x86_var.h>
 #include <x86/specialreg.h>