[compile]add Oz compile option for clang,test=develop

[Leonardo-Ding]

当使用clang编译时，使用-Oz替换-Os编译选项以取得更好优化库体积的效果； 对于develop分支，armv8/c++_shared编译，采用-Os编译，库体积2.0M，采用-Oz编译，库体积1.9M，优化了0.1M的库体积。 armv8/c++_static编译，采用-Os编译，库体积2.4M，采用-Oz编译，库体积2.2M，优化了0.2M的库体积。

[paddle-bot-old[bot]]

Thanks for your contribution!

[DannyIsFunny]

https://emscripten.org/docs/optimizing/Optimizing-Code.html 不知道会不会对性能有影响还是影响比较小呢，可以QA测试一下吗

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