SDL2: unexpected hash

Original issue: https://github.com/emscripten-ports/SDL2/issues/120

The problem is still happening here with recent emscripten versions :/

```
FAILED: 3rdparty/libossia/src/kfr_build/detect_cpu.js
: && /opt/emsdk/upstream/emscripten/em++ -std=c++20 -O2 -g -DNDEBUG -s USE_SDL=2 3rdparty/libossia/src/kfr_build/CMakeFiles/detect_cpu.dir/Unity/unity_0_cxx.cxx.o -o 3rdparty/libossia/src/kfr_build/detect_cpu.js -lstdc++ -lpthread -lm && :
ports:INFO: retrieving port: sdl2 from https://github.com/libsdl-org/SDL/archive/4b8d69a41687e5f6f4b05f7fd9804dd9fcac0347.zip
em++: error: Unexpected hash: 03e154a70b262153fe5a8794d1803daddeffd7126c8b90ba1e7ba867c22c7ebc1a73b11e41f4b79d82c283ad8a5d518261b6939d19a33d3474096a39da5aecb2
If you are updating the port, please update the hash.
```

I tried downloading https://github.com/libsdl-org/SDL/archive/4b8d69a41687e5f6f4b05f7fd9804dd9fcac0347.zip with wget / curl and it gives me:

```
$ sha512sum 4b8d69a41687e5f6f4b05f7fd9804dd9fcac0347.zip
2d4d577c7584da22306b05a44bc08200460a33cd414fed2dc948e2a86e7b2d1a5cbc13bacadb63618823ba63c210f21c570adbab39f7645bf902196fa91c6b4e 4b8d69a41687e5f6f4b05f7fd9804dd9fcac0347.zip
```

(the .zip is indeed the SDL source)