A clean DEV environment(vm + win10 + vs2017 only) may help.

• ActivePerl：http://www.activestate.com/activeperl/downloads
• openssl：https://www.openssl.org/source/
• libcurl https://curl.haxx.se/download.html

• launch x64 Native Tools Command Prompt for VS2017
• unzip and enter openssl folder
• run cmds:

perl Configure VC-WIN64I no-asm no-tests
ms\do_ms.bat
nmake -f ms\nt.mak

unicows.lib could not found

• use Everything to find it, copy to C:\Program Files (x86)\Windows Kits\10\Lib\10.0.16299.0\um\x64\

ssleay32.lib libeay32.lib

• launch x64 Native Tools Command Prompt for VS2017
• unzip and enter curl folder
• mkdir build && cd build
• cmake -G "Visual Studio 15 2017 Win64" ..
• open sln, in libcurl project properties
• add preprocessor USE_OPENSSL;CRYPT32
• add include directory openssl
• add libraries ssleay32.lib;libeay32.lib

• add preprocessor CURL_STATICLIB
• add include directory curl
• add libraries libcurl.lib;crypt32.lib