Refresh downstream runtime changes on LLVM 22

[arsnyder16]

This refreshes the downstream LLVM 22 runtime patches from Emscripten main at e13ee988ce3d, using system/lib/push_llvm_changes.py before porting them to LLVM 23.

The outstanding source changes are in libc++abi and libunwind, including the shared Wasm landing-pad context header. The shared compiler-rt sources already match the LLVM 22 fork branch. Generated configuration and Emscripten packaging files remain in the Emscripten repository, as in previous refreshes.

This is preparation for emscripten-core/emscripten#27808 and emscripten-core/emscripten#27992.

[github-actions]

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