Please post the following so people can help you:
1. Error message.
2. Build Log file
3. Compiler used and version and where it was downloaded from.
4. Version of wxWidget you are building against.
5. C::B version you are using to build C::B with
6. Version of Windows 10 you are using.
7. Exact command line used to download the C::B source
8. Command / script / process you used to build C::B
I checked the last nightly C::B, 12535 7z file and it includes the libtxml.a.
I suspect that the command you used to download the C::B source was wrong, but I am only guessing.