package/directfb: don't prepend $arch-linux- to programs

Directfb users: Do all those applications even make sense to install to
target?

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/directfb/directfb.mk

@@ -128,6 +128,7 @@ DIRECTFB_CONF_OPT = \
 	--enable-static \
 	--enable-shared \
 	--disable-explicit-deps \
+	--program-prefix='' \
 	$(DIRECTFB_MULTI) \
 	$(DIRECTFB_DEBUG) \
 	$(DIRECTFB_TRACE) \