V8 produces bogus signature mismatch errors for innocuous changes to the SDK

[John Plevyak]

Point master at the SDK at

https://github.com/proxy-wasm/proxy-wasm-cpp-sdk/tree/v8-signature-bug

and V8 will load the file, passing the signature check but then at runtime will fail the signature check for on_grpc_receive().

Note, the above patch does not effect that function and both the .wat file disassembly and all other signature checks pass.

[John Plevyak]

C++ exception with description "Function: proxy_on_grpc_receive failed: Uncaught RuntimeError: function signature mismatch" thrown in the test body.