fuzz testing: support Windows

[andrewrk]

Extracted from #20958.

zig build --fuzz does not work on Windows yet:

zig/lib/compiler/build_runner.zig

Lines 421 to 430 in 4381bac

	switch (builtin.os.tag) {
	// Current implementation depends on two things that need to be ported to Windows:
	// * Memory-mapping to share data between the fuzzer and build runner.
	// * COFF/PE support added to `std.debug.Info` (it needs a batching API for resolving
	// many addresses to source locations).
	.windows => fatal("--fuzz not yet implemented for {s}", .{@tagName(builtin.os.tag)}),
	else => {},
	}
	const listen_address = std.net.Address.parseIp("127.0.0.1", listen_port) catch unreachable;
	try Fuzz.start(

As noted in that comment, the current implementation depends on two things that need to be ported to Windows:

• Memory-mapping to share data between the fuzzer and build runner.
• COFF/PE support added to std.debug.Info (it needs a batching API for resolving many addresses to source locations).

To reproduce:

zig init
zig build test --fuzz