rsa-sign.c:279:21: error: dereferencing pointer to incomplete type 'RSA {aka struct rsa_st}'

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ubuntu16.04 编译openwrt_widora遇到这个问题，补丁来自：
https://github.com/openwrt/openwrt/commit/70b104f98c0657323b28fce140b73a94bf3eb756#diff-ad001f3a51a1d957d5013650f14df0cb
手动在tools/mkimage/patches/下增加该文件即可。