Sourcemap absolute path issue

Please include the following in your bug report:

**Version of emscripten/emsdk:**
Please include the output `emcc -v` here
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.32 (eab98adf462c39f3c31d348331c4830bcaa36949)
clang version 17.0.0 (https://github.com/llvm/llvm-project df82394e7a2d06506718cafa347bf7827c79fc4f)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\Users\diete\emsdk\upstream\bin

emscripten is installed on drive C:\
the project is installed on drive D:\
sourcemap entries point correctly to relative paths on D:\
sourcemap entries use an unusable absolute path for emscripten related files

Test project including a simple sourcemap:
https://github.com/dwz8/emtest