Fix build with mbedtls3.6

[msdos03]

MbedTLS have released its new stable version 3.6 since Mar 28 this year. Many linux distributions are switching to it now. Shadowsocks-libev build fails with mbedtls3.0+ version. https://github.com/shadowsocks/shadowsocks-libev/issues/2868 This issue stops distributions such as debian from migrating to mbedtls3.6. Since this is a bug-fix only port, I hope to be able to fix this problem upstream. Some of the reasons for the changes can be found here: https://github.com/fw876/helloworld/issues/1504 @madeye