Update against Zig's new build API

build.zig

@@ -1,19 +1,22 @@
 const std = @import("std");
 
-pub fn build(b: *std.build.Builder) void {
+pub fn build(b: *std.Build) void {
     // Standard target options allows the person running `zig build` to choose
     // what target to build for. Here we do not override the defaults, which
     // means any target is allowed, and the default is native. Other options
     // for restricting supported target set are available.
     const target = b.standardTargetOptions(.{});
 
-    // Standard release options allow the person running `zig build` to select
-    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
-    const mode = b.standardReleaseOptions();
+    // Standard optimization options allow the person running `zig build`
+    // to select between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
+    const optimize = b.standardOptimizeOption(.{});
 
-    const exe = b.addExecutable("user-map", "src/main.zig");
-    exe.setTarget(target);
-    exe.setBuildMode(mode);
+    const exe = b.addExecutable(.{
+        .name = "user-map",
+        .root_source_file = .{ .path = "src/main.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
     exe.install();
 
     const run_cmd = exe.run();