Add openbsd archs

Signed-off-by: Guillaume J. Charmes <git+guillaume@charmes.net>
diff --git a/test_crosscompile.sh b/test_crosscompile.sh
index f0b1dca..c4b9e37 100755
--- a/test_crosscompile.sh
+++ b/test_crosscompile.sh
@@ -29,7 +29,7 @@
 cross darwin    amd64 386 arm arm64
 cross freebsd   amd64 386 arm
 cross netbsd    amd64 386 arm
-cross openbsd   amd64 386
+cross openbsd   amd64 386 arm arm64
 cross dragonfly amd64
 cross solaris   amd64