综合两位 网上大神的 方法，完美解决。
大神出处一：https://juejin.im/post/5bc404255188255c4258529f
大神出处二：http://blog.anbig.com/2019/11/08/usr-lib-libstdc-6-dylib-mach-o-but-not-built-for-ios-simulator/
解决方法
真机
将libstdc_iPhoneOS拷贝到/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/lib
模拟器
将libstdc_iPhoneSimulator拷贝到/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/lib/
将libstdc_iPhoneSimulator_runtime拷贝到/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib/
