This patch fixes WebAssembly's FastISel pass to correctly consider
signext/zeroext parameter flags at function declaration.
Previously, the flags at call sites were only considered during code
generation, which caused an interesting bug report #63388 .
This is problematic especially because in WebAssembly's ABI, either
signext or zeroext can be tagged to a function argument, and it must be
correctly reflected in the generated code. Unit test
https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/WebAssembly/signext-zeroext.ll
shows that `i8 zeroext %t` and `i8 signext %t`'s code gen are different.
7388b7422f