Update README.md

README.md

@@ -27,6 +27,15 @@ cd OpenWrt-SDK-15.05-ramips-rt305x_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64
 git clone git@github.com:chenhaowen01/gdut-drcom.git package/gdut-drcom
 make package/gdut-drcom/compile
 ```
+* 主机编译
+```bash
+git clone git@github.com:chenhaowen01/gdut-drcom.git
+cd gdut-drcom/src
+# 可通过cryptlib变量指定加密库，留空表示不使用第三方库
+# cryptlib=[openssl, polarssl, gcrypt]
+# 如
+make cryptlib=openssl
+```
 # usage
 ```bash
 gdut-drcom