[libcxxabi] [libunwind] [libcxx] [libunwind][libcxx][libcxxabi] Fix Exception Handling build for wasm (PR #79667)

[Louis Dionne via cfe-commits]

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@@ -180,6 +180,7 @@
 #endif
 #define _LIBUNWIND_HIGHEST_DWARF_REGISTER                                      \
   _LIBUNWIND_HIGHEST_DWARF_REGISTER_LOONGARCH
+#elif defined(__wasm__)
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ldionne wrote:

Why don't we define `_LIBUNWIND_CURSOR_SIZE` and friends on wasm?

https://github.com/llvm/llvm-project/pull/79667