The default iwasm building in Windows MSVC enables libc-uvwasi because
libc-wasi isn't supported at the beginning. Since libc-wasi had been refactored
and is supported in Windows msys2 building, and libc-wasi supports more
functionalities(e.g. sockets) than libc-uvwasi, this PR fixes some issues to
enable libc-wasi in windows MSVC buidlings.
b16b6044ee