Make WASI and w2c2_base.h compile on MSVC 4.0

[SergioFLS]

Why MSVC 4.0 specifically? Mostly because it's the only compiler that I'm aware of that can target the RISC versions of Windows NT 4.0 (yes, there were official versions for MIPS, PowerPC and Alpha).

Generated code will still not compile with it though, as there's no long long type in MSVC4. You can replace all LL suffixes with i64 though, around c.c:1049:

w2c2/w2c2/c.c

Lines 1047 to 1050 in 22a9ade

	case wasmValueTypeI64: {
	MUST (stringBuilderAppendI64(builder, value.i64))
	MUST (stringBuilderAppend(builder, "ULL"))
	break;

The only reason that I didn't include it in this PR is that I wasn't able to find a way to add a type toggle switch while making the code pretty. (UPDATE: Made a W2C2_LL macro, no need for this anymore.)

There's still stuff to do to get the generated code to work completely with MSVC4, such as finding workarounds to the following errors:

• error C2520: conversion from unsigned __int64 to double not implemented, use signed __int64
• fatal error C1053: 'fXXXX' : function too large

Also, while not exactly fatal, the endianness check fails on MIPS for some reason (untested on PowerPC and Alpha).

Those errors come from the Python example, although I was able to get the ls and Rust examples working from the current patches.

[turbolent]

Nice, thank you for adding support for that compiler 👍