Make this repo build again about wasmtime-zig

[kubkon]

I took a look and the missing symbols are provided by libunwind (also note that the errors pop up in the first place since Zig/lld will prefer linking against static libs first). Zig ships libunwind and so we only need to explicitly specify that we want to link against in the build.zig script. Here's the diff, feel free to use it and no attribution is necessary:

diff --git a/build.zig b/build.zig
index 0b07c15..9c5ab2b 100644
--- a/build.zig
+++ b/build.zig
@@ -33,10 +33,19 @@ pub fn build(b: *std.build.Builder) !void {
         .source = .{ .path = "src/main.zig" },
         .dependencies = &.{pkgs.wasm},
     });
-    if (builtin.os.tag == .windows) {
-        simple_exe.linkSystemLibrary("wasmtime.dll");
-    } else {
-        simple_exe.linkSystemLibrary("wasmtime");
+    switch (builtin.os.tag) {
+        .windows => {
+            simple_exe.linkSystemLibrary("wasmtime.dll");
+            simple_exe.linkSystemLibrary("unwind");
+        },
+        .linux => {
+            simple_exe.linkSystemLibrary("wasmtime");
+            simple_exe.linkSystemLibrary("unwind");
+        },
+        .macos => {
+            simple_exe.linkSystemLibrary("wasmtime");
+        },
+        else => unreachable,
     }
     simple_exe.linkLibC();
     simple_exe.step.dependOn(b.getInstallStep());

Note that on macOS we always link dynamically and libcand libunwind are provided by the OS and always available so no need to link against it there.

Once you get everything building again, I'd really appreciate a PR with the fixed :-)

[voigt]

Thanks a lot, @kubkon, for looking into the problem.

I was able to incorporate your changes into build.zig. While Linux finally builds, Windows still complains about "FILENOTFOUND" stuff...

D:\a\wasmtime-zig\wasmtime-zig\zig-windows-x86_64-0.10.0-dev.2473+e498fb155\lib\std\os\windows.zig:1593:32: 0x7ff78d4627eb in td.os.windows.CreateProcessW (build.obj)
            .FILE_NOT_FOUND => return error.FileNotFound,

I'd appreciate it if you could have another look.

Apart from that, I started fixing the examples. This might take a couple of days (currently a bit limited in time)

Once you get everything building again, I'd appreciate a PR with the fixed :-)

This is my goal :)