[bindings] Switch genbindings.sh to wasm32-wasi from wasm32-unknown

This will switch to use the clang/C WASM ABI instead of the
wasm_bindgen WASM ABI as of rustc 1.51 (or nightly since [1]),
allowing us to link C and Rust code in a single wasm binary.

[1] rust-lang/rust#79998

Author: TheBlueMatt

genbindings.sh

@@ -175,8 +175,8 @@ else
 	echo "WARNING: Can't use address sanitizer on non-Linux, non-OSX non-x86 platforms"
 fi
 
-cargo rustc -v --target=wasm32-unknown-unknown -- -C embed-bitcode=yes || echo "WARNING: Failed to generate WASM LLVM-bitcode-embedded library"
-CARGO_PROFILE_RELEASE_LTO=true cargo rustc -v --release --target=wasm32-unknown-unknown -- -C opt-level=s -C linker-plugin-lto -C lto || echo "WARNING: Failed to generate WASM LLVM-bitcode-embedded optimized library"
+cargo rustc -v --target=wasm32-wasi -- -C embed-bitcode=yes || echo "WARNING: Failed to generate WASM LLVM-bitcode-embedded library"
+CARGO_PROFILE_RELEASE_LTO=true cargo rustc -v --release --target=wasm32-wasi -- -C opt-level=s -C linker-plugin-lto -C lto || echo "WARNING: Failed to generate WASM LLVM-bitcode-embedded optimized library"
 
 # Now build with LTO on on both C++ and rust, but without cross-language LTO:
 CARGO_PROFILE_RELEASE_LTO=true cargo rustc -v --release -- -C lto