Host Environment

• OS: Ubuntu 20.04
• Compiler: gcc 9.3.0

To Reproduce
Steps to reproduce the behavior:
./vcpkg install boost-filesystem:wasm32-emscripten

Failure logs

• Output to console: boost-filesystem_output.log
• Log file: boost-filesystem_install-wasm32-emscripten-dbg-out.log

Additional context
It used to work properly until a few days ago; build of 2021-08-12 (69670b0) can compile the same properly. A similar issue with boost-date-time #20537 may be related.