package/diffutils: drop host variant

It was only used by opkg-utils, but we now rely on the host system
provided diffutils.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 2d366a2ad26ac16b9d2c7ab5980a5301d21bf391)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/diffutils/diffutils.mk

@@ -20,4 +20,3 @@ DIFFUTILS_CONF_ENV += gl_cv_func_getopt_gnu=yes
 endif
 
 $(eval $(autotools-package))
-$(eval $(host-autotools-package))