Add --target option to build
Add --target option to build

Default is x86_64-unknown-linux-gnu.  To build 32 bit stratisd on a
64 bit system:

rustup target add i686-unknown-linux-gnu
dnf install -y dbus-devel.i686 systemd-devel.i686 glibc-devel.i686

TARGET=i686-unknown-linux-gnu make build

Signed-off-by: Todd Gill <7afbb5ba98932b8ffb9cc9e6675c4792db142529@redhat.com>

mulkieran/stratisd,trgill/stratisd,mulkieran/stratisd,stratis-storage/stratisd,stratis-storage/stratisd,trgill/stratisd,stratis-storage/stratisd