mrsas: unbreak i386 build

Fix build regression introduced by
e34a057ca6ebdf8e30ec8b0dc21d18eb450bf36a

Reviewed by: jhibbits
Sponsored by: Eldorado Research Institute (eldorado.org.br)
Differential Revision: https://reviews.freebsd.org/D28494

(cherry picked from commit 59fffbcf46ba6369420e655ff9173571410c643d)