toolchain: hardcoded docker as output type

target/toolchain/config.in

@@ -26,7 +26,8 @@ for x in CCACHE_USEIT=1 GCC_JAVA=0 \
 	export SDECFGSET_PKG_$x
 done
 
-SDECFGSET_IMAGE='none'
+SDECFGSET_IMAGE='docker'
+SDECFGSET_INIT='none'
 SDECFGSET_XTRACE='1'
 
 if [ ! -s "$cfgtmpdir/$target.config.in" ]; then