sysaudio: improve backend selection; remove i8 sample support (#767)

* sysaudio: fix compilation errors
* re-order backend selection
* remove i8 samples support from backends and disable signedToSigned convertion for now
* update sine-wave example

libs/sysaudio/sdk.zig

@@ -16,7 +16,9 @@ pub fn Sdk(comptime deps: anytype) type {
             _module = b.createModule(.{
                 .source_file = .{ .path = sdkPath("/src/main.zig") },
                 .dependencies = &.{
-                    .{ .name = "sysjs", .module = deps.sysjs.module(b) },
+                    .{ .name = "sysjs", .module = b.createModule(.{
+                        .source_file = .{ .path = "libs/mach-sysjs/src/main.zig" },
+                    }) },
                 },
             });
             return _module.?;