Fix build.sh for toolchain.

Change-Id: I38b7201e4317c930b797c1c2710cda86d223d61d
diff --git a/build.sh b/build.sh
index 4943e94..3c6b547 100755
--- a/build.sh
+++ b/build.sh
@@ -5,6 +5,11 @@
 	exit 1
 fi
 
+if [ ! -d ~/openwrt_toolchains ];then
+	echo "Start download toolchains."
+	git clone "ssh://b.liu@192.168.1.198:29418/mbtk_toolchains_for_asr_linux" ~/openwrt_toolchains && scp -p -P 29418 b.liu@192.168.1.198:hooks/commit-msg ~/openwrt_toolchains/.git/hooks/
+fi
+
 # static / shared
 export BUILD_LIB_TYPE=shared